1373 lines
49 KiB
Plaintext
1373 lines
49 KiB
Plaintext
# SOME DESCRIPTIVE TITLE.
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# Copyright (C) 2001-2016, Python Software Foundation
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# This file is distributed under the same license as the Python package.
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# FIRST AUTHOR <EMAIL@ADDRESS>, YEAR.
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#
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#, fuzzy
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msgid ""
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msgstr ""
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"Project-Id-Version: Python 3.6\n"
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"Report-Msgid-Bugs-To: \n"
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"POT-Creation-Date: 2017-05-27 19:40+0200\n"
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"PO-Revision-Date: YEAR-MO-DA HO:MI+ZONE\n"
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"Last-Translator: FULL NAME <EMAIL@ADDRESS>\n"
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"Language-Team: LANGUAGE <LL@li.org>\n"
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"Language: fr\n"
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"MIME-Version: 1.0\n"
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"Content-Type: text/plain; charset=UTF-8\n"
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"Content-Transfer-Encoding: 8bit\n"
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#: ../Doc/howto/functional.rst:3
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msgid "Functional Programming HOWTO"
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msgstr ""
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#: ../Doc/howto/functional.rst:0
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msgid "Author"
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msgstr ""
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#: ../Doc/howto/functional.rst:5
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msgid "A. M. Kuchling"
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msgstr ""
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#: ../Doc/howto/functional.rst:0
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msgid "Release"
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msgstr "Version"
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#: ../Doc/howto/functional.rst:6
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msgid "0.32"
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msgstr ""
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#: ../Doc/howto/functional.rst:8
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msgid ""
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"In this document, we'll take a tour of Python's features suitable for "
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"implementing programs in a functional style. After an introduction to the "
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"concepts of functional programming, we'll look at language features such as :"
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"term:`iterator`\\s and :term:`generator`\\s and relevant library modules "
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"such as :mod:`itertools` and :mod:`functools`."
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msgstr ""
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#: ../Doc/howto/functional.rst:16
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msgid "Introduction"
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msgstr "Introduction"
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#: ../Doc/howto/functional.rst:18
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msgid ""
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"This section explains the basic concept of functional programming; if you're "
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"just interested in learning about Python language features, skip to the next "
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"section on :ref:`functional-howto-iterators`."
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msgstr ""
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#: ../Doc/howto/functional.rst:22
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msgid ""
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"Programming languages support decomposing problems in several different ways:"
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msgstr ""
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#: ../Doc/howto/functional.rst:24
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msgid ""
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"Most programming languages are **procedural**: programs are lists of "
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"instructions that tell the computer what to do with the program's input. C, "
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"Pascal, and even Unix shells are procedural languages."
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msgstr ""
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#: ../Doc/howto/functional.rst:28
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msgid ""
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"In **declarative** languages, you write a specification that describes the "
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"problem to be solved, and the language implementation figures out how to "
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"perform the computation efficiently. SQL is the declarative language you're "
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"most likely to be familiar with; a SQL query describes the data set you want "
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"to retrieve, and the SQL engine decides whether to scan tables or use "
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"indexes, which subclauses should be performed first, etc."
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msgstr ""
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#: ../Doc/howto/functional.rst:35
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msgid ""
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"**Object-oriented** programs manipulate collections of objects. Objects "
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"have internal state and support methods that query or modify this internal "
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"state in some way. Smalltalk and Java are object-oriented languages. C++ "
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"and Python are languages that support object-oriented programming, but don't "
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"force the use of object-oriented features."
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msgstr ""
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#: ../Doc/howto/functional.rst:41
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msgid ""
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"**Functional** programming decomposes a problem into a set of functions. "
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"Ideally, functions only take inputs and produce outputs, and don't have any "
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"internal state that affects the output produced for a given input. Well-"
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"known functional languages include the ML family (Standard ML, OCaml, and "
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"other variants) and Haskell."
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msgstr ""
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#: ../Doc/howto/functional.rst:47
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msgid ""
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"The designers of some computer languages choose to emphasize one particular "
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"approach to programming. This often makes it difficult to write programs "
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"that use a different approach. Other languages are multi-paradigm languages "
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"that support several different approaches. Lisp, C++, and Python are multi-"
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"paradigm; you can write programs or libraries that are largely procedural, "
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"object-oriented, or functional in all of these languages. In a large "
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"program, different sections might be written using different approaches; the "
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"GUI might be object-oriented while the processing logic is procedural or "
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"functional, for example."
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msgstr ""
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#: ../Doc/howto/functional.rst:58
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msgid ""
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"In a functional program, input flows through a set of functions. Each "
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"function operates on its input and produces some output. Functional style "
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"discourages functions with side effects that modify internal state or make "
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"other changes that aren't visible in the function's return value. Functions "
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"that have no side effects at all are called **purely functional**. Avoiding "
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"side effects means not using data structures that get updated as a program "
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"runs; every function's output must only depend on its input."
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msgstr ""
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#: ../Doc/howto/functional.rst:66
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msgid ""
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"Some languages are very strict about purity and don't even have assignment "
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"statements such as ``a=3`` or ``c = a + b``, but it's difficult to avoid all "
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"side effects. Printing to the screen or writing to a disk file are side "
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"effects, for example. For example, in Python a call to the :func:`print` "
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"or :func:`time.sleep` function both return no useful value; they're only "
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"called for their side effects of sending some text to the screen or pausing "
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"execution for a second."
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msgstr ""
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#: ../Doc/howto/functional.rst:74
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msgid ""
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"Python programs written in functional style usually won't go to the extreme "
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"of avoiding all I/O or all assignments; instead, they'll provide a "
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"functional-appearing interface but will use non-functional features "
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"internally. For example, the implementation of a function will still use "
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"assignments to local variables, but won't modify global variables or have "
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"other side effects."
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msgstr ""
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#: ../Doc/howto/functional.rst:80
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msgid ""
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"Functional programming can be considered the opposite of object-oriented "
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"programming. Objects are little capsules containing some internal state "
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"along with a collection of method calls that let you modify this state, and "
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"programs consist of making the right set of state changes. Functional "
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"programming wants to avoid state changes as much as possible and works with "
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"data flowing between functions. In Python you might combine the two "
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"approaches by writing functions that take and return instances representing "
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"objects in your application (e-mail messages, transactions, etc.)."
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msgstr ""
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#: ../Doc/howto/functional.rst:89
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msgid ""
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"Functional design may seem like an odd constraint to work under. Why should "
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"you avoid objects and side effects? There are theoretical and practical "
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"advantages to the functional style:"
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msgstr ""
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#: ../Doc/howto/functional.rst:93
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msgid "Formal provability."
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msgstr ""
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#: ../Doc/howto/functional.rst:94
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msgid "Modularity."
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msgstr ""
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#: ../Doc/howto/functional.rst:95
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msgid "Composability."
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msgstr ""
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#: ../Doc/howto/functional.rst:96
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msgid "Ease of debugging and testing."
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msgstr ""
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#: ../Doc/howto/functional.rst:100
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msgid "Formal provability"
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msgstr ""
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#: ../Doc/howto/functional.rst:102
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msgid ""
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"A theoretical benefit is that it's easier to construct a mathematical proof "
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"that a functional program is correct."
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msgstr ""
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#: ../Doc/howto/functional.rst:105
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msgid ""
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"For a long time researchers have been interested in finding ways to "
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"mathematically prove programs correct. This is different from testing a "
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"program on numerous inputs and concluding that its output is usually "
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"correct, or reading a program's source code and concluding that the code "
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"looks right; the goal is instead a rigorous proof that a program produces "
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"the right result for all possible inputs."
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msgstr ""
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#: ../Doc/howto/functional.rst:112
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msgid ""
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"The technique used to prove programs correct is to write down "
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"**invariants**, properties of the input data and of the program's variables "
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"that are always true. For each line of code, you then show that if "
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"invariants X and Y are true **before** the line is executed, the slightly "
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"different invariants X' and Y' are true **after** the line is executed. "
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"This continues until you reach the end of the program, at which point the "
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"invariants should match the desired conditions on the program's output."
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msgstr ""
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#: ../Doc/howto/functional.rst:120
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msgid ""
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"Functional programming's avoidance of assignments arose because assignments "
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"are difficult to handle with this technique; assignments can break "
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"invariants that were true before the assignment without producing any new "
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"invariants that can be propagated onward."
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msgstr ""
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#: ../Doc/howto/functional.rst:125
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msgid ""
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"Unfortunately, proving programs correct is largely impractical and not "
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"relevant to Python software. Even trivial programs require proofs that are "
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"several pages long; the proof of correctness for a moderately complicated "
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"program would be enormous, and few or none of the programs you use daily "
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"(the Python interpreter, your XML parser, your web browser) could be proven "
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"correct. Even if you wrote down or generated a proof, there would then be "
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"the question of verifying the proof; maybe there's an error in it, and you "
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"wrongly believe you've proved the program correct."
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msgstr ""
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#: ../Doc/howto/functional.rst:136
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msgid "Modularity"
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msgstr ""
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#: ../Doc/howto/functional.rst:138
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msgid ""
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"A more practical benefit of functional programming is that it forces you to "
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"break apart your problem into small pieces. Programs are more modular as a "
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"result. It's easier to specify and write a small function that does one "
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"thing than a large function that performs a complicated transformation. "
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"Small functions are also easier to read and to check for errors."
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msgstr ""
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#: ../Doc/howto/functional.rst:146
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msgid "Ease of debugging and testing"
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msgstr ""
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#: ../Doc/howto/functional.rst:148
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msgid "Testing and debugging a functional-style program is easier."
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msgstr ""
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#: ../Doc/howto/functional.rst:150
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msgid ""
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"Debugging is simplified because functions are generally small and clearly "
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"specified. When a program doesn't work, each function is an interface point "
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"where you can check that the data are correct. You can look at the "
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"intermediate inputs and outputs to quickly isolate the function that's "
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"responsible for a bug."
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msgstr ""
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#: ../Doc/howto/functional.rst:155
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msgid ""
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"Testing is easier because each function is a potential subject for a unit "
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"test. Functions don't depend on system state that needs to be replicated "
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"before running a test; instead you only have to synthesize the right input "
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"and then check that the output matches expectations."
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msgstr ""
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#: ../Doc/howto/functional.rst:162
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msgid "Composability"
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msgstr ""
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#: ../Doc/howto/functional.rst:164
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msgid ""
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"As you work on a functional-style program, you'll write a number of "
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"functions with varying inputs and outputs. Some of these functions will be "
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"unavoidably specialized to a particular application, but others will be "
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"useful in a wide variety of programs. For example, a function that takes a "
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"directory path and returns all the XML files in the directory, or a function "
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"that takes a filename and returns its contents, can be applied to many "
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"different situations."
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msgstr ""
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#: ../Doc/howto/functional.rst:171
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msgid ""
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"Over time you'll form a personal library of utilities. Often you'll "
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"assemble new programs by arranging existing functions in a new configuration "
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"and writing a few functions specialized for the current task."
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msgstr ""
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#: ../Doc/howto/functional.rst:179
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msgid "Iterators"
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msgstr "Itérateurs"
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#: ../Doc/howto/functional.rst:181
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msgid ""
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"I'll start by looking at a Python language feature that's an important "
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"foundation for writing functional-style programs: iterators."
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msgstr ""
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#: ../Doc/howto/functional.rst:184
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msgid ""
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"An iterator is an object representing a stream of data; this object returns "
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"the data one element at a time. A Python iterator must support a method "
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"called :meth:`~iterator.__next__` that takes no arguments and always returns "
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"the next element of the stream. If there are no more elements in the "
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"stream, :meth:`~iterator.__next__` must raise the :exc:`StopIteration` "
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"exception. Iterators don't have to be finite, though; it's perfectly "
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"reasonable to write an iterator that produces an infinite stream of data."
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msgstr ""
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#: ../Doc/howto/functional.rst:192
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msgid ""
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"The built-in :func:`iter` function takes an arbitrary object and tries to "
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"return an iterator that will return the object's contents or elements, "
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"raising :exc:`TypeError` if the object doesn't support iteration. Several "
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"of Python's built-in data types support iteration, the most common being "
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"lists and dictionaries. An object is called :term:`iterable` if you can get "
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"an iterator for it."
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msgstr ""
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#: ../Doc/howto/functional.rst:199
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msgid "You can experiment with the iteration interface manually:"
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msgstr ""
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#: ../Doc/howto/functional.rst:217
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msgid ""
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"Python expects iterable objects in several different contexts, the most "
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"important being the :keyword:`for` statement. In the statement ``for X in "
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"Y``, Y must be an iterator or some object for which :func:`iter` can create "
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"an iterator. These two statements are equivalent::"
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msgstr ""
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#: ../Doc/howto/functional.rst:229
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msgid ""
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"Iterators can be materialized as lists or tuples by using the :func:`list` "
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"or :func:`tuple` constructor functions:"
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msgstr ""
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#: ../Doc/howto/functional.rst:238
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msgid ""
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"Sequence unpacking also supports iterators: if you know an iterator will "
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"return N elements, you can unpack them into an N-tuple:"
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msgstr ""
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#: ../Doc/howto/functional.rst:247
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msgid ""
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"Built-in functions such as :func:`max` and :func:`min` can take a single "
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"iterator argument and will return the largest or smallest element. The ``"
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"\"in\"`` and ``\"not in\"`` operators also support iterators: ``X in "
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"iterator`` is true if X is found in the stream returned by the iterator. "
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"You'll run into obvious problems if the iterator is infinite; :func:`max`, :"
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"func:`min` will never return, and if the element X never appears in the "
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"stream, the ``\"in\"`` and ``\"not in\"`` operators won't return either."
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msgstr ""
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#: ../Doc/howto/functional.rst:255
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msgid ""
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"Note that you can only go forward in an iterator; there's no way to get the "
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"previous element, reset the iterator, or make a copy of it. Iterator "
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"objects can optionally provide these additional capabilities, but the "
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"iterator protocol only specifies the :meth:`~iterator.__next__` method. "
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"Functions may therefore consume all of the iterator's output, and if you "
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"need to do something different with the same stream, you'll have to create a "
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"new iterator."
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msgstr ""
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#: ../Doc/howto/functional.rst:265
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msgid "Data Types That Support Iterators"
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msgstr ""
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#: ../Doc/howto/functional.rst:267
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msgid ""
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"We've already seen how lists and tuples support iterators. In fact, any "
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"Python sequence type, such as strings, will automatically support creation "
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"of an iterator."
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msgstr ""
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#: ../Doc/howto/functional.rst:271
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msgid ""
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"Calling :func:`iter` on a dictionary returns an iterator that will loop over "
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"the dictionary's keys::"
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msgstr ""
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#: ../Doc/howto/functional.rst:291
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msgid ""
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"Note that the order is essentially random, because it's based on the hash "
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"ordering of the objects in the dictionary."
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msgstr ""
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#: ../Doc/howto/functional.rst:294
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||
msgid ""
|
||
"Applying :func:`iter` to a dictionary always loops over the keys, but "
|
||
"dictionaries have methods that return other iterators. If you want to "
|
||
"iterate over values or key/value pairs, you can explicitly call the :meth:"
|
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"`~dict.values` or :meth:`~dict.items` methods to get an appropriate iterator."
|
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msgstr ""
|
||
|
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#: ../Doc/howto/functional.rst:300
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||
msgid ""
|
||
"The :func:`dict` constructor can accept an iterator that returns a finite "
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"stream of ``(key, value)`` tuples:"
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msgstr ""
|
||
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||
#: ../Doc/howto/functional.rst:307
|
||
msgid ""
|
||
"Files also support iteration by calling the :meth:`~io.TextIOBase.readline` "
|
||
"method until there are no more lines in the file. This means you can read "
|
||
"each line of a file like this::"
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:315
|
||
msgid ""
|
||
"Sets can take their contents from an iterable and let you iterate over the "
|
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"set's elements::"
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||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:325
|
||
msgid "Generator expressions and list comprehensions"
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msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:327
|
||
msgid ""
|
||
"Two common operations on an iterator's output are 1) performing some "
|
||
"operation for every element, 2) selecting a subset of elements that meet "
|
||
"some condition. For example, given a list of strings, you might want to "
|
||
"strip off trailing whitespace from each line or extract all the strings "
|
||
"containing a given substring."
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:333
|
||
msgid ""
|
||
"List comprehensions and generator expressions (short form: \"listcomps\" and "
|
||
"\"genexps\") are a concise notation for such operations, borrowed from the "
|
||
"functional programming language Haskell (https://www.haskell.org/). You can "
|
||
"strip all the whitespace from a stream of strings with the following code::"
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:346
|
||
msgid ""
|
||
"You can select only certain elements by adding an ``\"if\"`` condition::"
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:351
|
||
msgid ""
|
||
"With a list comprehension, you get back a Python list; ``stripped_list`` is "
|
||
"a list containing the resulting lines, not an iterator. Generator "
|
||
"expressions return an iterator that computes the values as necessary, not "
|
||
"needing to materialize all the values at once. This means that list "
|
||
"comprehensions aren't useful if you're working with iterators that return an "
|
||
"infinite stream or a very large amount of data. Generator expressions are "
|
||
"preferable in these situations."
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:358
|
||
msgid ""
|
||
"Generator expressions are surrounded by parentheses (\"()\") and list "
|
||
"comprehensions are surrounded by square brackets (\"[]\"). Generator "
|
||
"expressions have the form::"
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:371
|
||
msgid ""
|
||
"Again, for a list comprehension only the outside brackets are different "
|
||
"(square brackets instead of parentheses)."
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||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:374
|
||
msgid ""
|
||
"The elements of the generated output will be the successive values of "
|
||
"``expression``. The ``if`` clauses are all optional; if present, "
|
||
"``expression`` is only evaluated and added to the result when ``condition`` "
|
||
"is true."
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:378
|
||
msgid ""
|
||
"Generator expressions always have to be written inside parentheses, but the "
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||
"parentheses signalling a function call also count. If you want to create an "
|
||
"iterator that will be immediately passed to a function you can write::"
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:384
|
||
msgid ""
|
||
"The ``for...in`` clauses contain the sequences to be iterated over. The "
|
||
"sequences do not have to be the same length, because they are iterated over "
|
||
"from left to right, **not** in parallel. For each element in ``sequence1``, "
|
||
"``sequence2`` is looped over from the beginning. ``sequence3`` is then "
|
||
"looped over for each resulting pair of elements from ``sequence1`` and "
|
||
"``sequence2``."
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:390
|
||
msgid ""
|
||
"To put it another way, a list comprehension or generator expression is "
|
||
"equivalent to the following Python code::"
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:407
|
||
msgid ""
|
||
"This means that when there are multiple ``for...in`` clauses but no ``if`` "
|
||
"clauses, the length of the resulting output will be equal to the product of "
|
||
"the lengths of all the sequences. If you have two lists of length 3, the "
|
||
"output list is 9 elements long:"
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:419
|
||
msgid ""
|
||
"To avoid introducing an ambiguity into Python's grammar, if ``expression`` "
|
||
"is creating a tuple, it must be surrounded with parentheses. The first list "
|
||
"comprehension below is a syntax error, while the second one is correct::"
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:430
|
||
msgid "Generators"
|
||
msgstr "Générateurs"
|
||
|
||
#: ../Doc/howto/functional.rst:432
|
||
msgid ""
|
||
"Generators are a special class of functions that simplify the task of "
|
||
"writing iterators. Regular functions compute a value and return it, but "
|
||
"generators return an iterator that returns a stream of values."
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:436
|
||
msgid ""
|
||
"You're doubtless familiar with how regular function calls work in Python or "
|
||
"C. When you call a function, it gets a private namespace where its local "
|
||
"variables are created. When the function reaches a ``return`` statement, "
|
||
"the local variables are destroyed and the value is returned to the caller. "
|
||
"A later call to the same function creates a new private namespace and a "
|
||
"fresh set of local variables. But, what if the local variables weren't "
|
||
"thrown away on exiting a function? What if you could later resume the "
|
||
"function where it left off? This is what generators provide; they can be "
|
||
"thought of as resumable functions."
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:445
|
||
msgid "Here's the simplest example of a generator function:"
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:451
|
||
msgid ""
|
||
"Any function containing a :keyword:`yield` keyword is a generator function; "
|
||
"this is detected by Python's :term:`bytecode` compiler which compiles the "
|
||
"function specially as a result."
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:455
|
||
msgid ""
|
||
"When you call a generator function, it doesn't return a single value; "
|
||
"instead it returns a generator object that supports the iterator protocol. "
|
||
"On executing the ``yield`` expression, the generator outputs the value of "
|
||
"``i``, similar to a ``return`` statement. The big difference between "
|
||
"``yield`` and a ``return`` statement is that on reaching a ``yield`` the "
|
||
"generator's state of execution is suspended and local variables are "
|
||
"preserved. On the next call to the generator's :meth:`~generator.__next__` "
|
||
"method, the function will resume executing."
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:464
|
||
msgid "Here's a sample usage of the ``generate_ints()`` generator:"
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:481
|
||
msgid ""
|
||
"You could equally write ``for i in generate_ints(5)``, or ``a,b,c = "
|
||
"generate_ints(3)``."
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:484
|
||
msgid ""
|
||
"Inside a generator function, ``return value`` causes "
|
||
"``StopIteration(value)`` to be raised from the :meth:`~generator.__next__` "
|
||
"method. Once this happens, or the bottom of the function is reached, the "
|
||
"procession of values ends and the generator cannot yield any further values."
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:489
|
||
msgid ""
|
||
"You could achieve the effect of generators manually by writing your own "
|
||
"class and storing all the local variables of the generator as instance "
|
||
"variables. For example, returning a list of integers could be done by "
|
||
"setting ``self.count`` to 0, and having the :meth:`~iterator.__next__` "
|
||
"method increment ``self.count`` and return it. However, for a moderately "
|
||
"complicated generator, writing a corresponding class can be much messier."
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:497
|
||
msgid ""
|
||
"The test suite included with Python's library, :source:`Lib/test/"
|
||
"test_generators.py`, contains a number of more interesting examples. Here's "
|
||
"one generator that implements an in-order traversal of a tree using "
|
||
"generators recursively. ::"
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:513
|
||
msgid ""
|
||
"Two other examples in ``test_generators.py`` produce solutions for the N-"
|
||
"Queens problem (placing N queens on an NxN chess board so that no queen "
|
||
"threatens another) and the Knight's Tour (finding a route that takes a "
|
||
"knight to every square of an NxN chessboard without visiting any square "
|
||
"twice)."
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:521
|
||
msgid "Passing values into a generator"
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:523
|
||
msgid ""
|
||
"In Python 2.4 and earlier, generators only produced output. Once a "
|
||
"generator's code was invoked to create an iterator, there was no way to pass "
|
||
"any new information into the function when its execution is resumed. You "
|
||
"could hack together this ability by making the generator look at a global "
|
||
"variable or by passing in some mutable object that callers then modify, but "
|
||
"these approaches are messy."
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:530
|
||
msgid ""
|
||
"In Python 2.5 there's a simple way to pass values into a generator. :keyword:"
|
||
"`yield` became an expression, returning a value that can be assigned to a "
|
||
"variable or otherwise operated on::"
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:536
|
||
msgid ""
|
||
"I recommend that you **always** put parentheses around a ``yield`` "
|
||
"expression when you're doing something with the returned value, as in the "
|
||
"above example. The parentheses aren't always necessary, but it's easier to "
|
||
"always add them instead of having to remember when they're needed."
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:541
|
||
msgid ""
|
||
"(:pep:`342` explains the exact rules, which are that a ``yield``-expression "
|
||
"must always be parenthesized except when it occurs at the top-level "
|
||
"expression on the right-hand side of an assignment. This means you can "
|
||
"write ``val = yield i`` but have to use parentheses when there's an "
|
||
"operation, as in ``val = (yield i) + 12``.)"
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:547
|
||
msgid ""
|
||
"Values are sent into a generator by calling its :meth:`send(value) "
|
||
"<generator.send>` method. This method resumes the generator's code and the "
|
||
"``yield`` expression returns the specified value. If the regular :meth:"
|
||
"`~generator.__next__` method is called, the ``yield`` returns ``None``."
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:552
|
||
msgid ""
|
||
"Here's a simple counter that increments by 1 and allows changing the value "
|
||
"of the internal counter."
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:567
|
||
msgid "And here's an example of changing the counter:"
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:584
|
||
msgid ""
|
||
"Because ``yield`` will often be returning ``None``, you should always check "
|
||
"for this case. Don't just use its value in expressions unless you're sure "
|
||
"that the :meth:`~generator.send` method will be the only method used to "
|
||
"resume your generator function."
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:589
|
||
msgid ""
|
||
"In addition to :meth:`~generator.send`, there are two other methods on "
|
||
"generators:"
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:592
|
||
msgid ""
|
||
":meth:`throw(type, value=None, traceback=None) <generator.throw>` is used to "
|
||
"raise an exception inside the generator; the exception is raised by the "
|
||
"``yield`` expression where the generator's execution is paused."
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:596
|
||
msgid ""
|
||
":meth:`~generator.close` raises a :exc:`GeneratorExit` exception inside the "
|
||
"generator to terminate the iteration. On receiving this exception, the "
|
||
"generator's code must either raise :exc:`GeneratorExit` or :exc:"
|
||
"`StopIteration`; catching the exception and doing anything else is illegal "
|
||
"and will trigger a :exc:`RuntimeError`. :meth:`~generator.close` will also "
|
||
"be called by Python's garbage collector when the generator is garbage-"
|
||
"collected."
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:604
|
||
msgid ""
|
||
"If you need to run cleanup code when a :exc:`GeneratorExit` occurs, I "
|
||
"suggest using a ``try: ... finally:`` suite instead of catching :exc:"
|
||
"`GeneratorExit`."
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:607
|
||
msgid ""
|
||
"The cumulative effect of these changes is to turn generators from one-way "
|
||
"producers of information into both producers and consumers."
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:610
|
||
msgid ""
|
||
"Generators also become **coroutines**, a more generalized form of "
|
||
"subroutines. Subroutines are entered at one point and exited at another "
|
||
"point (the top of the function, and a ``return`` statement), but coroutines "
|
||
"can be entered, exited, and resumed at many different points (the ``yield`` "
|
||
"statements)."
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:617
|
||
msgid "Built-in functions"
|
||
msgstr "Fonctions Natives"
|
||
|
||
#: ../Doc/howto/functional.rst:619
|
||
msgid ""
|
||
"Let's look in more detail at built-in functions often used with iterators."
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:621
|
||
msgid ""
|
||
"Two of Python's built-in functions, :func:`map` and :func:`filter` duplicate "
|
||
"the features of generator expressions:"
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:633
|
||
msgid ""
|
||
":func:`map(f, iterA, iterB, ...) <map>` returns an iterator over the sequence"
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:625
|
||
msgid ""
|
||
"``f(iterA[0], iterB[0]), f(iterA[1], iterB[1]), f(iterA[2], iterB[2]), ...``."
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:635
|
||
msgid "You can of course achieve the same effect with a list comprehension."
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:637
|
||
msgid ""
|
||
":func:`filter(predicate, iter) <filter>` returns an iterator over all the "
|
||
"sequence elements that meet a certain condition, and is similarly duplicated "
|
||
"by list comprehensions. A **predicate** is a function that returns the "
|
||
"truth value of some condition; for use with :func:`filter`, the predicate "
|
||
"must take a single value."
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:650
|
||
msgid "This can also be written as a list comprehension:"
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:656
|
||
msgid ""
|
||
":func:`enumerate(iter) <enumerate>` counts off the elements in the iterable, "
|
||
"returning 2-tuples containing the count and each element. ::"
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:665
|
||
msgid ""
|
||
":func:`enumerate` is often used when looping through a list and recording "
|
||
"the indexes at which certain conditions are met::"
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:673
|
||
msgid ""
|
||
":func:`sorted(iterable, key=None, reverse=False) <sorted>` collects all the "
|
||
"elements of the iterable into a list, sorts the list, and returns the sorted "
|
||
"result. The *key* and *reverse* arguments are passed through to the "
|
||
"constructed list's :meth:`~list.sort` method. ::"
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:688
|
||
msgid ""
|
||
"(For a more detailed discussion of sorting, see the :ref:`sortinghowto`.)"
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:691
|
||
msgid ""
|
||
"The :func:`any(iter) <any>` and :func:`all(iter) <all>` built-ins look at "
|
||
"the truth values of an iterable's contents. :func:`any` returns ``True`` if "
|
||
"any element in the iterable is a true value, and :func:`all` returns "
|
||
"``True`` if all of the elements are true values:"
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:710
|
||
msgid ""
|
||
":func:`zip(iterA, iterB, ...) <zip>` takes one element from each iterable "
|
||
"and returns them in a tuple::"
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:716
|
||
msgid ""
|
||
"It doesn't construct an in-memory list and exhaust all the input iterators "
|
||
"before returning; instead tuples are constructed and returned only if "
|
||
"they're requested. (The technical term for this behaviour is `lazy "
|
||
"evaluation <https://en.wikipedia.org/wiki/Lazy_evaluation>`__.)"
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:721
|
||
msgid ""
|
||
"This iterator is intended to be used with iterables that are all of the same "
|
||
"length. If the iterables are of different lengths, the resulting stream "
|
||
"will be the same length as the shortest iterable. ::"
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:728
|
||
msgid ""
|
||
"You should avoid doing this, though, because an element may be taken from "
|
||
"the longer iterators and discarded. This means you can't go on to use the "
|
||
"iterators further because you risk skipping a discarded element."
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:734
|
||
msgid "The itertools module"
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:736
|
||
msgid ""
|
||
"The :mod:`itertools` module contains a number of commonly-used iterators as "
|
||
"well as functions for combining several iterators. This section will "
|
||
"introduce the module's contents by showing small examples."
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:740
|
||
msgid "The module's functions fall into a few broad classes:"
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:742
|
||
msgid "Functions that create a new iterator based on an existing iterator."
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:743
|
||
msgid "Functions for treating an iterator's elements as function arguments."
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:744
|
||
msgid "Functions for selecting portions of an iterator's output."
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:745
|
||
msgid "A function for grouping an iterator's output."
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:748
|
||
msgid "Creating new iterators"
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:750
|
||
msgid ""
|
||
":func:`itertools.count(n) <itertools.count>` returns an infinite stream of "
|
||
"integers, increasing by 1 each time. You can optionally supply the starting "
|
||
"number, which defaults to 0::"
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:759
|
||
msgid ""
|
||
":func:`itertools.cycle(iter) <itertools.cycle>` saves a copy of the contents "
|
||
"of a provided iterable and returns a new iterator that returns its elements "
|
||
"from first to last. The new iterator will repeat these elements "
|
||
"infinitely. ::"
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:766
|
||
msgid ""
|
||
":func:`itertools.repeat(elem, [n]) <itertools.repeat>` returns the provided "
|
||
"element *n* times, or returns the element endlessly if *n* is not "
|
||
"provided. ::"
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:774
|
||
msgid ""
|
||
":func:`itertools.chain(iterA, iterB, ...) <itertools.chain>` takes an "
|
||
"arbitrary number of iterables as input, and returns all the elements of the "
|
||
"first iterator, then all the elements of the second, and so on, until all of "
|
||
"the iterables have been exhausted. ::"
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:782
|
||
msgid ""
|
||
":func:`itertools.islice(iter, [start], stop, [step]) <itertools.islice>` "
|
||
"returns a stream that's a slice of the iterator. With a single *stop* "
|
||
"argument, it will return the first *stop* elements. If you supply a "
|
||
"starting index, you'll get *stop-start* elements, and if you supply a value "
|
||
"for *step*, elements will be skipped accordingly. Unlike Python's string "
|
||
"and list slicing, you can't use negative values for *start*, *stop*, or "
|
||
"*step*. ::"
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:796
|
||
msgid ""
|
||
":func:`itertools.tee(iter, [n]) <itertools.tee>` replicates an iterator; it "
|
||
"returns *n* independent iterators that will all return the contents of the "
|
||
"source iterator. If you don't supply a value for *n*, the default is 2. "
|
||
"Replicating iterators requires saving some of the contents of the source "
|
||
"iterator, so this can consume significant memory if the iterator is large "
|
||
"and one of the new iterators is consumed more than the others. ::"
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:815
|
||
msgid "Calling functions on elements"
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:817
|
||
msgid ""
|
||
"The :mod:`operator` module contains a set of functions corresponding to "
|
||
"Python's operators. Some examples are :func:`operator.add(a, b) <operator."
|
||
"add>` (adds two values), :func:`operator.ne(a, b) <operator.ne>` (same as "
|
||
"``a != b``), and :func:`operator.attrgetter('id') <operator.attrgetter>` "
|
||
"(returns a callable that fetches the ``.id`` attribute)."
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:823
|
||
msgid ""
|
||
":func:`itertools.starmap(func, iter) <itertools.starmap>` assumes that the "
|
||
"iterable will return a stream of tuples, and calls *func* using these tuples "
|
||
"as the arguments::"
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:835
|
||
msgid "Selecting elements"
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:837
|
||
msgid ""
|
||
"Another group of functions chooses a subset of an iterator's elements based "
|
||
"on a predicate."
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:840
|
||
msgid ""
|
||
":func:`itertools.filterfalse(predicate, iter) <itertools.filterfalse>` is "
|
||
"the opposite of :func:`filter`, returning all elements for which the "
|
||
"predicate returns false::"
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:847
|
||
msgid ""
|
||
":func:`itertools.takewhile(predicate, iter) <itertools.takewhile>` returns "
|
||
"elements for as long as the predicate returns true. Once the predicate "
|
||
"returns false, the iterator will signal the end of its results. ::"
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:860
|
||
msgid ""
|
||
":func:`itertools.dropwhile(predicate, iter) <itertools.dropwhile>` discards "
|
||
"elements while the predicate returns true, and then returns the rest of the "
|
||
"iterable's results. ::"
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:870
|
||
msgid ""
|
||
":func:`itertools.compress(data, selectors) <itertools.compress>` takes two "
|
||
"iterators and returns only those elements of *data* for which the "
|
||
"corresponding element of *selectors* is true, stopping whenever either one "
|
||
"is exhausted::"
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:879
|
||
msgid "Combinatoric functions"
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:881
|
||
msgid ""
|
||
"The :func:`itertools.combinations(iterable, r) <itertools.combinations>` "
|
||
"returns an iterator giving all possible *r*-tuple combinations of the "
|
||
"elements contained in *iterable*. ::"
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:896
|
||
msgid ""
|
||
"The elements within each tuple remain in the same order as *iterable* "
|
||
"returned them. For example, the number 1 is always before 2, 3, 4, or 5 in "
|
||
"the examples above. A similar function, :func:`itertools."
|
||
"permutations(iterable, r=None) <itertools.permutations>`, removes this "
|
||
"constraint on the order, returning all possible arrangements of length *r*::"
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:915
|
||
msgid ""
|
||
"If you don't supply a value for *r* the length of the iterable is used, "
|
||
"meaning that all the elements are permuted."
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:918
|
||
msgid ""
|
||
"Note that these functions produce all of the possible combinations by "
|
||
"position and don't require that the contents of *iterable* are unique::"
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:925
|
||
msgid ""
|
||
"The identical tuple ``('a', 'a', 'b')`` occurs twice, but the two 'a' "
|
||
"strings came from different positions."
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:928
|
||
msgid ""
|
||
"The :func:`itertools.combinations_with_replacement(iterable, r) <itertools."
|
||
"combinations_with_replacement>` function relaxes a different constraint: "
|
||
"elements can be repeated within a single tuple. Conceptually an element is "
|
||
"selected for the first position of each tuple and then is replaced before "
|
||
"the second element is selected. ::"
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:943
|
||
msgid "Grouping elements"
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:945
|
||
msgid ""
|
||
"The last function I'll discuss, :func:`itertools.groupby(iter, "
|
||
"key_func=None) <itertools.groupby>`, is the most complicated. "
|
||
"``key_func(elem)`` is a function that can compute a key value for each "
|
||
"element returned by the iterable. If you don't supply a key function, the "
|
||
"key is simply each element itself."
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:950
|
||
msgid ""
|
||
":func:`~itertools.groupby` collects all the consecutive elements from the "
|
||
"underlying iterable that have the same key value, and returns a stream of 2-"
|
||
"tuples containing a key value and an iterator for the elements with that key."
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:978
|
||
msgid ""
|
||
":func:`~itertools.groupby` assumes that the underlying iterable's contents "
|
||
"will already be sorted based on the key. Note that the returned iterators "
|
||
"also use the underlying iterable, so you have to consume the results of "
|
||
"iterator-1 before requesting iterator-2 and its corresponding key."
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:985
|
||
msgid "The functools module"
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:987
|
||
msgid ""
|
||
"The :mod:`functools` module in Python 2.5 contains some higher-order "
|
||
"functions. A **higher-order function** takes one or more functions as input "
|
||
"and returns a new function. The most useful tool in this module is the :"
|
||
"func:`functools.partial` function."
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:992
|
||
msgid ""
|
||
"For programs written in a functional style, you'll sometimes want to "
|
||
"construct variants of existing functions that have some of the parameters "
|
||
"filled in. Consider a Python function ``f(a, b, c)``; you may wish to create "
|
||
"a new function ``g(b, c)`` that's equivalent to ``f(1, b, c)``; you're "
|
||
"filling in a value for one of ``f()``'s parameters. This is called "
|
||
"\"partial function application\"."
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:998
|
||
msgid ""
|
||
"The constructor for :func:`~functools.partial` takes the arguments "
|
||
"``(function, arg1, arg2, ..., kwarg1=value1, kwarg2=value2)``. The "
|
||
"resulting object is callable, so you can just call it to invoke ``function`` "
|
||
"with the filled-in arguments."
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:1003
|
||
msgid "Here's a small but realistic example::"
|
||
msgstr "Voici un exemple court mais réaliste ::"
|
||
|
||
#: ../Doc/howto/functional.rst:1015
|
||
msgid ""
|
||
":func:`functools.reduce(func, iter, [initial_value]) <functools.reduce>` "
|
||
"cumulatively performs an operation on all the iterable's elements and, "
|
||
"therefore, can't be applied to infinite iterables. *func* must be a function "
|
||
"that takes two elements and returns a single value. :func:`functools."
|
||
"reduce` takes the first two elements A and B returned by the iterator and "
|
||
"calculates ``func(A, B)``. It then requests the third element, C, "
|
||
"calculates ``func(func(A, B), C)``, combines this result with the fourth "
|
||
"element returned, and continues until the iterable is exhausted. If the "
|
||
"iterable returns no values at all, a :exc:`TypeError` exception is raised. "
|
||
"If the initial value is supplied, it's used as a starting point and "
|
||
"``func(initial_value, A)`` is the first calculation. ::"
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:1039
|
||
msgid ""
|
||
"If you use :func:`operator.add` with :func:`functools.reduce`, you'll add up "
|
||
"all the elements of the iterable. This case is so common that there's a "
|
||
"special built-in called :func:`sum` to compute it:"
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:1051
|
||
msgid ""
|
||
"For many uses of :func:`functools.reduce`, though, it can be clearer to just "
|
||
"write the obvious :keyword:`for` loop::"
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:1063
|
||
msgid ""
|
||
"A related function is `itertools.accumulate(iterable, func=operator.add) "
|
||
"<itertools.accumulate`. It performs the same calculation, but instead of "
|
||
"returning only the final result, :func:`accumulate` returns an iterator that "
|
||
"also yields each partial result::"
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:1076
|
||
msgid "The operator module"
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:1078
|
||
msgid ""
|
||
"The :mod:`operator` module was mentioned earlier. It contains a set of "
|
||
"functions corresponding to Python's operators. These functions are often "
|
||
"useful in functional-style code because they save you from writing trivial "
|
||
"functions that perform a single operation."
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:1083
|
||
msgid "Some of the functions in this module are:"
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:1085
|
||
msgid ""
|
||
"Math operations: ``add()``, ``sub()``, ``mul()``, ``floordiv()``, "
|
||
"``abs()``, ..."
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:1086
|
||
msgid "Logical operations: ``not_()``, ``truth()``."
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:1087
|
||
msgid "Bitwise operations: ``and_()``, ``or_()``, ``invert()``."
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:1088
|
||
msgid ""
|
||
"Comparisons: ``eq()``, ``ne()``, ``lt()``, ``le()``, ``gt()``, and ``ge()``."
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:1089
|
||
msgid "Object identity: ``is_()``, ``is_not()``."
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:1091
|
||
msgid "Consult the operator module's documentation for a complete list."
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:1095
|
||
msgid "Small functions and the lambda expression"
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:1097
|
||
msgid ""
|
||
"When writing functional-style programs, you'll often need little functions "
|
||
"that act as predicates or that combine elements in some way."
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:1100
|
||
msgid ""
|
||
"If there's a Python built-in or a module function that's suitable, you don't "
|
||
"need to define a new function at all::"
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:1106
|
||
msgid ""
|
||
"If the function you need doesn't exist, you need to write it. One way to "
|
||
"write small functions is to use the :keyword:`lambda` statement. ``lambda`` "
|
||
"takes a number of parameters and an expression combining these parameters, "
|
||
"and creates an anonymous function that returns the value of the expression::"
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:1115
|
||
msgid ""
|
||
"An alternative is to just use the ``def`` statement and define a function in "
|
||
"the usual way::"
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:1124
|
||
msgid ""
|
||
"Which alternative is preferable? That's a style question; my usual course "
|
||
"is to avoid using ``lambda``."
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:1127
|
||
msgid ""
|
||
"One reason for my preference is that ``lambda`` is quite limited in the "
|
||
"functions it can define. The result has to be computable as a single "
|
||
"expression, which means you can't have multiway ``if... elif... else`` "
|
||
"comparisons or ``try... except`` statements. If you try to do too much in a "
|
||
"``lambda`` statement, you'll end up with an overly complicated expression "
|
||
"that's hard to read. Quick, what's the following code doing? ::"
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:1137
|
||
msgid ""
|
||
"You can figure it out, but it takes time to disentangle the expression to "
|
||
"figure out what's going on. Using a short nested ``def`` statements makes "
|
||
"things a little bit better::"
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:1147
|
||
msgid "But it would be best of all if I had simply used a ``for`` loop::"
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:1153
|
||
msgid "Or the :func:`sum` built-in and a generator expression::"
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:1157
|
||
msgid ""
|
||
"Many uses of :func:`functools.reduce` are clearer when written as ``for`` "
|
||
"loops."
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:1159
|
||
msgid ""
|
||
"Fredrik Lundh once suggested the following set of rules for refactoring uses "
|
||
"of ``lambda``:"
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:1162
|
||
msgid "Write a lambda function."
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:1163
|
||
msgid "Write a comment explaining what the heck that lambda does."
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:1164
|
||
msgid ""
|
||
"Study the comment for a while, and think of a name that captures the essence "
|
||
"of the comment."
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:1166
|
||
msgid "Convert the lambda to a def statement, using that name."
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:1167
|
||
msgid "Remove the comment."
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:1169
|
||
msgid ""
|
||
"I really like these rules, but you're free to disagree about whether this "
|
||
"lambda-free style is better."
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:1174
|
||
msgid "Revision History and Acknowledgements"
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:1176
|
||
msgid ""
|
||
"The author would like to thank the following people for offering "
|
||
"suggestions, corrections and assistance with various drafts of this article: "
|
||
"Ian Bicking, Nick Coghlan, Nick Efford, Raymond Hettinger, Jim Jewett, Mike "
|
||
"Krell, Leandro Lameiro, Jussi Salmela, Collin Winter, Blake Winton."
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:1181
|
||
msgid "Version 0.1: posted June 30 2006."
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:1183
|
||
msgid "Version 0.11: posted July 1 2006. Typo fixes."
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:1185
|
||
msgid ""
|
||
"Version 0.2: posted July 10 2006. Merged genexp and listcomp sections into "
|
||
"one. Typo fixes."
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:1188
|
||
msgid ""
|
||
"Version 0.21: Added more references suggested on the tutor mailing list."
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:1190
|
||
msgid ""
|
||
"Version 0.30: Adds a section on the ``functional`` module written by Collin "
|
||
"Winter; adds short section on the operator module; a few other edits."
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:1195
|
||
msgid "References"
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:1198
|
||
msgid "General"
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:1200
|
||
msgid ""
|
||
"**Structure and Interpretation of Computer Programs**, by Harold Abelson and "
|
||
"Gerald Jay Sussman with Julie Sussman. Full text at https://mitpress.mit."
|
||
"edu/sicp/. In this classic textbook of computer science, chapters 2 and 3 "
|
||
"discuss the use of sequences and streams to organize the data flow inside a "
|
||
"program. The book uses Scheme for its examples, but many of the design "
|
||
"approaches described in these chapters are applicable to functional-style "
|
||
"Python code."
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:1208
|
||
msgid ""
|
||
"http://www.defmacro.org/ramblings/fp.html: A general introduction to "
|
||
"functional programming that uses Java examples and has a lengthy historical "
|
||
"introduction."
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:1211
|
||
msgid ""
|
||
"https://en.wikipedia.org/wiki/Functional_programming: General Wikipedia "
|
||
"entry describing functional programming."
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:1214
|
||
msgid "https://en.wikipedia.org/wiki/Coroutine: Entry for coroutines."
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:1216
|
||
msgid ""
|
||
"https://en.wikipedia.org/wiki/Currying: Entry for the concept of currying."
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:1219
|
||
msgid "Python-specific"
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:1221
|
||
msgid ""
|
||
"http://gnosis.cx/TPiP/: The first chapter of David Mertz's book :title-"
|
||
"reference:`Text Processing in Python` discusses functional programming for "
|
||
"text processing, in the section titled \"Utilizing Higher-Order Functions in "
|
||
"Text Processing\"."
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:1226
|
||
msgid ""
|
||
"Mertz also wrote a 3-part series of articles on functional programming for "
|
||
"IBM's DeveloperWorks site; see `part 1 <https://www.ibm.com/developerworks/"
|
||
"linux/library/l-prog/index.html>`__, `part 2 <https://www.ibm.com/"
|
||
"developerworks/linux/library/l-prog2/index.html>`__, and `part 3 <https://"
|
||
"www.ibm.com/developerworks/linux/library/l-prog3/index.html>`__,"
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:1234
|
||
msgid "Python documentation"
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:1236
|
||
msgid "Documentation for the :mod:`itertools` module."
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:1238
|
||
msgid "Documentation for the :mod:`operator` module."
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:1240
|
||
msgid ":pep:`289`: \"Generator Expressions\""
|
||
msgstr ""
|
||
|
||
#: ../Doc/howto/functional.rst:1242
|
||
msgid ""
|
||
":pep:`342`: \"Coroutines via Enhanced Generators\" describes the new "
|
||
"generator features in Python 2.5."
|
||
msgstr ""
|