# SOME DESCRIPTIVE TITLE.

# Copyright (C) 2001-2024, Python Software Foundation

# This file is distributed under the same license as the Python package.

# FIRST AUTHOR <EMAIL@ADDRESS>, YEAR.

#

# Translators:

# ww song <[email protected]>, 2020

# ppcfish <[email protected]>, 2020

# Bryan不可思议, 2023

# Freesand Leo <[email protected]>, 2024

#

#, fuzzy

msgid ""

msgstr ""

"Project-Id-Version: Python 3.8\n"

"Report-Msgid-Bugs-To: \n"

"POT-Creation-Date: 2024-08-09 19:35+0000\n"

"PO-Revision-Date: 2020-05-30 12:17+0000\n"

"Last-Translator: Freesand Leo <[email protected]>, 2024\n"

"Language-Team: Chinese (China) (https://app.transifex.com/python-doc/teams/5390/zh_CN/)\n"

"MIME-Version: 1.0\n"

"Content-Type: text/plain; charset=UTF-8\n"

"Content-Transfer-Encoding: 8bit\n"

"Language: zh_CN\n"

"Plural-Forms: nplurals=1; plural=0;\n"

#: ../../whatsnew/2.4.rst:3

msgid "What's New in Python 2.4"

msgstr "Python 2.4 有什么新变化"

#: ../../whatsnew/2.4.rst:0

msgid "Author"

msgstr "作者"

#: ../../whatsnew/2.4.rst:5

msgid "A.M. Kuchling"

msgstr "A.M. Kuchling"

#: ../../whatsnew/2.4.rst:14

msgid ""

"This article explains the new features in Python 2.4.1, released on March "

"30, 2005."

msgstr "本文介绍了2005年3月30日发布的 Python 2.4.1 的新功能。"

#: ../../whatsnew/2.4.rst:17

msgid ""

"Python 2.4 is a medium-sized release. It doesn't introduce as many changes "

"as the radical Python 2.2, but introduces more features than the "

"conservative 2.3 release. The most significant new language features are "

"function decorators and generator expressions; most other changes are to the"

" standard library."

msgstr ""

"Python 2.4 是一个中等规模的发布版。 它引入的变化没有激进的 Python 2.2 那么多，但比保守的 2.3 发布版引入了更多的特性。 "

"最主要的新语言特性是函数装饰器和生成器表达式；其他大部分改动都是针对标准库。"

#: ../../whatsnew/2.4.rst:22

msgid ""

"According to the CVS change logs, there were 481 patches applied and 502 "

"bugs fixed between Python 2.3 and 2.4. Both figures are likely to be "

"underestimates."

msgstr ""

"根据 CVS 变更日志，Python 2.3 和 2.4 之间共应用了 481 个补丁并修复了 502 个错误。 这两个数字可能都被低估了。"

#: ../../whatsnew/2.4.rst:25

msgid ""

"This article doesn't attempt to provide a complete specification of every "

"single new feature, but instead provides a brief introduction to each "

"feature. For full details, you should refer to the documentation for Python"

" 2.4, such as the Python Library Reference and the Python Reference Manual."

" Often you will be referred to the PEP for a particular new feature for "

"explanations of the implementation and design rationale."

msgstr ""

"本文并不试图提供每一个新特性的完整规范说明，而是对每个特性进行简要的介绍。 要了解完整细节，你应该参考 Python 2.4 的文档，如 Python "

"库参考和 Python 参考手册等。 通常你需要参阅特定新特性的 PEP 以了解有关具体实现和设计原理的说明。"

#: ../../whatsnew/2.4.rst:36

msgid "PEP 218: Built-In Set Objects"

msgstr "PEP 218: 内置集合对象"

#: ../../whatsnew/2.4.rst:38

msgid ""

"Python 2.3 introduced the :mod:`sets` module. C implementations of set data"

" types have now been added to the Python core as two new built-in types, "

"``set(iterable)`` and ``frozenset(iterable)``. They provide high speed "

"operations for membership testing, for eliminating duplicates from "

"sequences, and for mathematical operations like unions, intersections, "

"differences, and symmetric differences. ::"

msgstr ""

"Python 2.3 引入了 :mod:`sets` 模块。 现在集合数据类型的 C 语言实现作为两个新的内置类型 ``set(iterable)`` "

"和 ``frozenset(iterable)`` 被添加到 Python 内核中。 "

"它们为成员测试、消除序列中的重复数据以及并集、交集、差集和对称差集等数学运算提供了高速操作。 ::"

#: ../../whatsnew/2.4.rst:71

msgid ""

"The :func:`frozenset` type is an immutable version of :func:`set`. Since it "

"is immutable and hashable, it may be used as a dictionary key or as a member"

" of another set."

msgstr ""

":func:`frozenset` 类型是 :func:`set` 的不可变版本。 "

"由于它是不可变且不可哈希的对象，因而可被用作字典的键或另一个集合的成员。"

#: ../../whatsnew/2.4.rst:75

msgid ""

"The :mod:`sets` module remains in the standard library, and may be useful if"

" you wish to subclass the :class:`Set` or :class:`ImmutableSet` classes. "

"There are currently no plans to deprecate the module."

msgstr ""

":mod:`sets` 模块仍被保留在标准库中，如果你想要子类化 :class:`Set` 或 :class:`ImmutableSet` "

"类时会很有用处。 目前还没有弃用该模块的计划。"

#: ../../whatsnew/2.4.rst:83

msgid ":pep:`218` - Adding a Built-In Set Object Type"

msgstr ":pep:`218` - 添加内置Set对象类型"

#: ../../whatsnew/2.4.rst:83

msgid ""

"Originally proposed by Greg Wilson and ultimately implemented by Raymond "

"Hettinger."

msgstr "最初由 Greg Wilson 提出，由 Raymond Hettinger 最终实现。"

#: ../../whatsnew/2.4.rst:90

msgid "PEP 237: Unifying Long Integers and Integers"

msgstr "PEP 237: 统一长整数和整数"

#: ../../whatsnew/2.4.rst:92

msgid ""

"The lengthy transition process for this PEP, begun in Python 2.2, takes "

"another step forward in Python 2.4. In 2.3, certain integer operations that"

" would behave differently after int/long unification triggered "

":exc:`FutureWarning` warnings and returned values limited to 32 or 64 bits "

"(depending on your platform). In 2.4, these expressions no longer produce a"

" warning and instead produce a different result that's usually a long "

"integer."

msgstr ""

#: ../../whatsnew/2.4.rst:99

msgid ""

"The problematic expressions are primarily left shifts and lengthy "

"hexadecimal and octal constants. For example, ``2 << 32`` results in a "

"warning in 2.3, evaluating to 0 on 32-bit platforms. In Python 2.4, this "

"expression now returns the correct answer, 8589934592."

msgstr ""

#: ../../whatsnew/2.4.rst:108

msgid ":pep:`237` - Unifying Long Integers and Integers"

msgstr ":pep:`237` - 统一长整数和整数"

#: ../../whatsnew/2.4.rst:108

msgid ""

"Original PEP written by Moshe Zadka and GvR. The changes for 2.4 were "

"implemented by Kalle Svensson."

msgstr "原始PEP由 Moshe Zadka 和 GvR 撰写，2.4 的变更由 Kalle Svensson 实现。"

#: ../../whatsnew/2.4.rst:115

msgid "PEP 289: Generator Expressions"

msgstr "PEP 289: 生成器表达式"

#: ../../whatsnew/2.4.rst:117

msgid ""

"The iterator feature introduced in Python 2.2 and the :mod:`itertools` "

"module make it easier to write programs that loop through large data sets "

"without having the entire data set in memory at one time. List "

"comprehensions don't fit into this picture very well because they produce a "

"Python list object containing all of the items. This unavoidably pulls all "

"of the objects into memory, which can be a problem if your data set is very "

"large. When trying to write a functionally-styled program, it would be "

"natural to write something like::"

msgstr ""

#: ../../whatsnew/2.4.rst:129

msgid "instead of ::"

msgstr "代替："

#: ../../whatsnew/2.4.rst:136

msgid ""

"The first form is more concise and perhaps more readable, but if you're "

"dealing with a large number of link objects you'd have to write the second "

"form to avoid having all link objects in memory at the same time."

msgstr ""

#: ../../whatsnew/2.4.rst:140

msgid ""

"Generator expressions work similarly to list comprehensions but don't "

"materialize the entire list; instead they create a generator that will "

"return elements one by one. The above example could be written as::"

msgstr ""

#: ../../whatsnew/2.4.rst:148

msgid ""

"Generator expressions always have to be written inside parentheses, as in "

"the above example. The parentheses signalling a function call also count, "

"so if you want to create an iterator that will be immediately passed to a "

"function you could write::"

msgstr ""

#: ../../whatsnew/2.4.rst:155

msgid ""

"Generator expressions differ from list comprehensions in various small ways."

" Most notably, the loop variable (*obj* in the above example) is not "

"accessible outside of the generator expression. List comprehensions leave "

"the variable assigned to its last value; future versions of Python will "

"change this, making list comprehensions match generator expressions in this "

"respect."

msgstr ""

#: ../../whatsnew/2.4.rst:165

msgid ":pep:`289` - Generator Expressions"

msgstr ":pep:`289` - 生成器表达式"

#: ../../whatsnew/2.4.rst:165

msgid ""

"Proposed by Raymond Hettinger and implemented by Jiwon Seo with early "

"efforts steered by Hye-Shik Chang."

msgstr ""

#: ../../whatsnew/2.4.rst:172

msgid "PEP 292: Simpler String Substitutions"

msgstr "PEP 292: 更简单的字符串替换"

#: ../../whatsnew/2.4.rst:174

msgid ""

"Some new classes in the standard library provide an alternative mechanism "

"for substituting variables into strings; this style of substitution may be "

"better for applications where untrained users need to edit templates."

msgstr ""

#: ../../whatsnew/2.4.rst:178

msgid ""

"The usual way of substituting variables by name is the ``%`` operator::"

msgstr "按名称替换变量的常用方式是 ``%`` 运算符::"

#: ../../whatsnew/2.4.rst:183

msgid ""

"When writing the template string, it can be easy to forget the ``i`` or "

"``s`` after the closing parenthesis. This isn't a big problem if the "

"template is in a Python module, because you run the code, get an "

"\"Unsupported format character\" :exc:`ValueError`, and fix the problem. "

"However, consider an application such as Mailman where template strings or "

"translations are being edited by users who aren't aware of the Python "

"language. The format string's syntax is complicated to explain to such "

"users, and if they make a mistake, it's difficult to provide helpful "

"feedback to them."

msgstr ""

#: ../../whatsnew/2.4.rst:192

msgid ""

"PEP 292 adds a :class:`Template` class to the :mod:`string` module that uses"

" ``$`` to indicate a substitution::"

msgstr "PEP 292 给 :mod:`string` 模块增加了一个 :class:`Template`，它使用 ``$`` 来表示替换::"

#: ../../whatsnew/2.4.rst:200

msgid ""

"If a key is missing from the dictionary, the :meth:`substitute` method will "

"raise a :exc:`KeyError`. There's also a :meth:`safe_substitute` method that"

" ignores missing keys::"

msgstr ""

"如果某个键在字典中找不到，:meth:`substitute` 方法将引发 :exc:`KeyError`。 还有一个 "

":meth:`safe_substitute` 方法则会忽略找不到的键::"

#: ../../whatsnew/2.4.rst:211

msgid ":pep:`292` - Simpler String Substitutions"

msgstr ":pep:`292` - 更简单的字符串替换"

#: ../../whatsnew/2.4.rst:212

msgid "Written and implemented by Barry Warsaw."

msgstr "由 Barry Warsaw 撰写并实现"

#: ../../whatsnew/2.4.rst:218

msgid "PEP 318: Decorators for Functions and Methods"

msgstr "PEP 318: 函数和方法的装饰器"

#: ../../whatsnew/2.4.rst:220

msgid ""

"Python 2.2 extended Python's object model by adding static methods and class"

" methods, but it didn't extend Python's syntax to provide any new way of "

"defining static or class methods. Instead, you had to write a "

":keyword:`def` statement in the usual way, and pass the resulting method to "

"a :func:`staticmethod` or :func:`classmethod` function that would wrap up "

"the function as a method of the new type. Your code would look like this::"

msgstr ""

#: ../../whatsnew/2.4.rst:233

msgid ""

"If the method was very long, it would be easy to miss or forget the "

":func:`classmethod` invocation after the function body."

msgstr ""

#: ../../whatsnew/2.4.rst:236

msgid ""

"The intention was always to add some syntax to make such definitions more "

"readable, but at the time of 2.2's release a good syntax was not obvious. "

"Today a good syntax *still* isn't obvious but users are asking for easier "

"access to the feature; a new syntactic feature has been added to meet this "

"need."

msgstr ""

#: ../../whatsnew/2.4.rst:241

msgid ""

"The new feature is called \"function decorators\". The name comes from the "

"idea that :func:`classmethod`, :func:`staticmethod`, and friends are storing"

" additional information on a function object; they're *decorating* functions"

" with more details."

msgstr ""

#: ../../whatsnew/2.4.rst:246

msgid ""

"The notation borrows from Java and uses the ``'@'`` character as an "

"indicator. Using the new syntax, the example above would be written::"

msgstr ""

#: ../../whatsnew/2.4.rst:256

msgid ""

"The ``@classmethod`` is shorthand for the ``meth=classmethod(meth)`` "

"assignment. More generally, if you have the following::"

msgstr ""

#: ../../whatsnew/2.4.rst:265

msgid "It's equivalent to the following pre-decorator code::"

msgstr "它等价于以下无装饰器的代码::"

#: ../../whatsnew/2.4.rst:270

msgid ""

"Decorators must come on the line before a function definition, one decorator"

" per line, and can't be on the same line as the def statement, meaning that "

"``@A def f(): ...`` is illegal. You can only decorate function definitions,"

" either at the module level or inside a class; you can't decorate class "

"definitions."

msgstr ""

#: ../../whatsnew/2.4.rst:275

msgid ""

"A decorator is just a function that takes the function to be decorated as an"

" argument and returns either the same function or some new object. The "

"return value of the decorator need not be callable (though it typically is),"

" unless further decorators will be applied to the result. It's easy to "

"write your own decorators. The following simple example just sets an "

"attribute on the function object::"

msgstr ""

#: ../../whatsnew/2.4.rst:295

msgid ""

"As a slightly more realistic example, the following decorator checks that "

"the supplied argument is an integer::"

msgstr ""

#: ../../whatsnew/2.4.rst:313

msgid ""

"An example in :pep:`318` contains a fancier version of this idea that lets "

"you both specify the required type and check the returned type."

msgstr ""

#: ../../whatsnew/2.4.rst:316

msgid ""

"Decorator functions can take arguments. If arguments are supplied, your "

"decorator function is called with only those arguments and must return a new"

" decorator function; this function must take a single function and return a "

"function, as previously described. In other words, ``@A @B @C(args)`` "

"becomes::"

msgstr ""

#: ../../whatsnew/2.4.rst:325

msgid ""

"Getting this right can be slightly brain-bending, but it's not too "

"difficult."

msgstr ""

#: ../../whatsnew/2.4.rst:327

msgid ""

"A small related change makes the :attr:`func_name` attribute of functions "

"writable. This attribute is used to display function names in tracebacks, "

"so decorators should change the name of any new function that's constructed "

"and returned."

msgstr ""

#: ../../whatsnew/2.4.rst:338

msgid ":pep:`318` - Decorators for Functions, Methods and Classes"

msgstr ":pep:`318` - 函数、方法和类的装饰器"

#: ../../whatsnew/2.4.rst:336

msgid ""

"Written by Kevin D. Smith, Jim Jewett, and Skip Montanaro. Several people "

"wrote patches implementing function decorators, but the one that was "

"actually checked in was patch #979728, written by Mark Russell."

msgstr ""

#: ../../whatsnew/2.4.rst:340

msgid "https://wiki.python.org/moin/PythonDecoratorLibrary"

msgstr "https://wiki.python.org/moin/PythonDecoratorLibrary"

#: ../../whatsnew/2.4.rst:341

msgid "This Wiki page contains several examples of decorators."

msgstr "该Wiki页面包含几个装饰器示例。"

#: ../../whatsnew/2.4.rst:347

msgid "PEP 322: Reverse Iteration"

msgstr "PEP 322: 反向迭代"

#: ../../whatsnew/2.4.rst:349

msgid ""

"A new built-in function, ``reversed(seq)``, takes a sequence and returns an "

"iterator that loops over the elements of the sequence in reverse order. "

"::"

msgstr ""

#: ../../whatsnew/2.4.rst:359

msgid ""

"Compared to extended slicing, such as ``range(1,4)[::-1]``, :func:`reversed`"

" is easier to read, runs faster, and uses substantially less memory."

msgstr ""

#: ../../whatsnew/2.4.rst:362

msgid ""

"Note that :func:`reversed` only accepts sequences, not arbitrary iterators."

" If you want to reverse an iterator, first convert it to a list with "

":func:`list`. ::"

msgstr ""

#: ../../whatsnew/2.4.rst:376

msgid ":pep:`322` - Reverse Iteration"

msgstr ":pep:`322` - 反向迭代"

#: ../../whatsnew/2.4.rst:377

msgid "Written and implemented by Raymond Hettinger."

msgstr "由 Raymond Hettinger 撰写并实现。"

#: ../../whatsnew/2.4.rst:383

msgid "PEP 324: New subprocess Module"

msgstr "PEP 324: 新的子进程模块"

#: ../../whatsnew/2.4.rst:385

msgid ""

"The standard library provides a number of ways to execute a subprocess, "

"offering different features and different levels of complexity. "

"``os.system(command)`` is easy to use, but slow (it runs a shell process "

"which executes the command) and dangerous (you have to be careful about "

"escaping the shell's metacharacters). The :mod:`popen2` module offers "

"classes that can capture standard output and standard error from the "

"subprocess, but the naming is confusing. The :mod:`subprocess` module "

"cleans this up, providing a unified interface that offers all the features "

"you might need."

msgstr ""

#: ../../whatsnew/2.4.rst:394

msgid ""

"Instead of :mod:`popen2`'s collection of classes, :mod:`subprocess` contains"

" a single class called :class:`Popen` whose constructor supports a number "

"of different keyword arguments. ::"

msgstr ""

#: ../../whatsnew/2.4.rst:404

msgid ""

"*args* is commonly a sequence of strings that will be the arguments to the "

"program executed as the subprocess. (If the *shell* argument is true, "

"*args* can be a string which will then be passed on to the shell for "

"interpretation, just as :func:`os.system` does.)"

msgstr ""

#: ../../whatsnew/2.4.rst:409

msgid ""

"*stdin*, *stdout*, and *stderr* specify what the subprocess's input, output,"

" and error streams will be. You can provide a file object or a file "

"descriptor, or you can use the constant ``subprocess.PIPE`` to create a pipe"

" between the subprocess and the parent."

msgstr ""

#: ../../whatsnew/2.4.rst:417

msgid "The constructor has a number of handy options:"

msgstr "此构造器有几个方便的选项:"

#: ../../whatsnew/2.4.rst:419

msgid ""

"*close_fds* requests that all file descriptors be closed before running the "

"subprocess."

msgstr "*close_fds* 将在运行子进程之前请求关闭所有文件描述符。"

#: ../../whatsnew/2.4.rst:422

msgid ""

"*cwd* specifies the working directory in which the subprocess will be "

"executed (defaulting to whatever the parent's working directory is)."

msgstr "*cwd* 指定执行子进程将使用的工作目录（默认为父进程的工作目录）。"

#: ../../whatsnew/2.4.rst:425

msgid "*env* is a dictionary specifying environment variables."

msgstr "*env* 是一个指定环境变量的字典。"

#: ../../whatsnew/2.4.rst:427

msgid ""

"*preexec_fn* is a function that gets called before the child is started."

msgstr "*preexec_fn* 是将在子进程启动之前被调用的函数。"

#: ../../whatsnew/2.4.rst:429

msgid ""

"*universal_newlines* opens the child's input and output using Python's "

":term:`universal newlines` feature."

msgstr ""

#: ../../whatsnew/2.4.rst:432

msgid ""

"Once you've created the :class:`Popen` instance, you can call its "

":meth:`wait` method to pause until the subprocess has exited, :meth:`poll` "

"to check if it's exited without pausing, or ``communicate(data)`` to send "

"the string *data* to the subprocess's standard input. "

"``communicate(data)`` then reads any data that the subprocess has sent to "

"its standard output or standard error, returning a tuple ``(stdout_data, "

"stderr_data)``."

msgstr ""

#: ../../whatsnew/2.4.rst:439

msgid ""

":func:`call` is a shortcut that passes its arguments along to the "

":class:`Popen` constructor, waits for the command to complete, and returns "

"the status code of the subprocess. It can serve as a safer analog to "

":func:`os.system`::"

msgstr ""

#: ../../whatsnew/2.4.rst:451

msgid ""

"The command is invoked without use of the shell. If you really do want to "

"use the shell, you can add ``shell=True`` as a keyword argument and provide "

"a string instead of a sequence::"

msgstr ""

#: ../../whatsnew/2.4.rst:457

msgid ""

"The PEP takes various examples of shell and Python code and shows how they'd"

" be translated into Python code that uses :mod:`subprocess`. Reading this "

"section of the PEP is highly recommended."

msgstr ""

#: ../../whatsnew/2.4.rst:465

msgid ":pep:`324` - subprocess - New process module"

msgstr ":pep:`324` - 子进程 - 新的进程模块"

#: ../../whatsnew/2.4.rst:465

msgid ""

"Written and implemented by Peter Åstrand, with assistance from Fredrik Lundh"

" and others."

msgstr "由 Peter Åstrand 在 Fredrik Lundh 等人的协助下撰写并实现。"

#: ../../whatsnew/2.4.rst:472

msgid "PEP 327: Decimal Data Type"

msgstr "PEP 327: 十进制数据类型"

#: ../../whatsnew/2.4.rst:474

msgid ""

"Python has always supported floating-point (FP) numbers, based on the "

"underlying C :c:type:`double` type, as a data type. However, while most "

"programming languages provide a floating-point type, many people (even "

"programmers) are unaware that floating-point numbers don't represent certain"

" decimal fractions accurately. The new :class:`Decimal` type can represent "

"these fractions accurately, up to a user-specified precision limit."

msgstr ""

#: ../../whatsnew/2.4.rst:483

msgid "Why is Decimal needed?"

msgstr "为什么需要十进制？"

#: ../../whatsnew/2.4.rst:485

msgid ""

"The limitations arise from the representation used for floating-point "

"numbers. FP numbers are made up of three components:"

msgstr ""

#: ../../whatsnew/2.4.rst:488

msgid "The sign, which is positive or negative."

msgstr ""

#: ../../whatsnew/2.4.rst:490

msgid ""

"The mantissa, which is a single-digit binary number followed by a "

"fractional part. For example, ``1.01`` in base-2 notation is ``1 + 0/2 + "

"1/4``, or 1.25 in decimal notation."

msgstr ""

#: ../../whatsnew/2.4.rst:494

msgid ""

"The exponent, which tells where the decimal point is located in the number "

"represented."

msgstr ""

#: ../../whatsnew/2.4.rst:497

msgid ""

"For example, the number 1.25 has positive sign, a mantissa value of 1.01 (in"

" binary), and an exponent of 0 (the decimal point doesn't need to be "

"shifted). The number 5 has the same sign and mantissa, but the exponent is 2"

" because the mantissa is multiplied by 4 (2 to the power of the exponent 2);"

" 1.25 \\* 4 equals 5."

msgstr ""

#: ../../whatsnew/2.4.rst:503

msgid ""

"Modern systems usually provide floating-point support that conforms to a "

"standard called IEEE 754. C's :c:type:`double` type is usually implemented "

"as a 64-bit IEEE 754 number, which uses 52 bits of space for the mantissa. "

"This means that numbers can only be specified to 52 bits of precision. If "

"you're trying to represent numbers whose expansion repeats endlessly, the "

"expansion is cut off after 52 bits. Unfortunately, most software needs to "

"produce output in base 10, and common fractions in base 10 are often "

"repeating decimals in binary. For example, 1.1 decimal is binary "

"``1.0001100110011 ...``; .1 = 1/16 + 1/32 + 1/256 plus an infinite number of"

" additional terms. IEEE 754 has to chop off that infinitely repeated "

"decimal after 52 digits, so the representation is slightly inaccurate."

msgstr ""

#: ../../whatsnew/2.4.rst:515

msgid "Sometimes you can see this inaccuracy when the number is printed::"

msgstr ""

#: ../../whatsnew/2.4.rst:520

msgid ""

"The inaccuracy isn't always visible when you print the number because the "

"FP-to-decimal-string conversion is provided by the C library, and most C "

"libraries try to produce sensible output. Even if it's not displayed, "

"however, the inaccuracy is still there and subsequent operations can magnify"

" the error."

msgstr ""

#: ../../whatsnew/2.4.rst:525

msgid ""

"For many applications this doesn't matter. If I'm plotting points and "

"displaying them on my monitor, the difference between 1.1 and "

"1.1000000000000001 is too small to be visible. Reports often limit output "

"to a certain number of decimal places, and if you round the number to two or"

" three or even eight decimal places, the error is never apparent. However, "

"for applications where it does matter, it's a lot of work to implement your"

" own custom arithmetic routines."

msgstr ""

#: ../../whatsnew/2.4.rst:533

msgid "Hence, the :class:`Decimal` type was created."

msgstr "因此，创建了 :class:`Decimal` 类型。"

#: ../../whatsnew/2.4.rst:537

msgid "The :class:`Decimal` type"

msgstr ":class:`Decimal` 类型"

#: ../../whatsnew/2.4.rst:539

msgid ""

"A new module, :mod:`decimal`, was added to Python's standard library. It "

"contains two classes, :class:`Decimal` and :class:`Context`. "

":class:`Decimal` instances represent numbers, and :class:`Context` instances"

" are used to wrap up various settings such as the precision and default "

"rounding mode."

msgstr ""

#: ../../whatsnew/2.4.rst:544

msgid ""

":class:`Decimal` instances are immutable, like regular Python integers and "

"FP numbers; once it's been created, you can't change the value an instance "

"represents. :class:`Decimal` instances can be created from integers or "

"strings::"

msgstr ""

#: ../../whatsnew/2.4.rst:555

msgid ""

"You can also provide tuples containing the sign, the mantissa represented "

"as a tuple of decimal digits, and the exponent::"

msgstr ""

#: ../../whatsnew/2.4.rst:561

msgid ""

"Cautionary note: the sign bit is a Boolean value, so 0 is positive and 1 is "

"negative."

msgstr ""

#: ../../whatsnew/2.4.rst:564

msgid ""

"Converting from floating-point numbers poses a bit of a problem: should the "

"FP number representing 1.1 turn into the decimal number for exactly 1.1, or "

"for 1.1 plus whatever inaccuracies are introduced? The decision was to dodge"

" the issue and leave such a conversion out of the API. Instead, you should "

"convert the floating-point number into a string using the desired precision "

"and pass the string to the :class:`Decimal` constructor::"

msgstr ""

#: ../../whatsnew/2.4.rst:577

msgid ""

"Once you have :class:`Decimal` instances, you can perform the usual "

"mathematical operations on them. One limitation: exponentiation requires an"

" integer exponent::"

msgstr ""

#: ../../whatsnew/2.4.rst:598

msgid ""

"You can combine :class:`Decimal` instances with integers, but not with "

"floating-point numbers::"

msgstr ""

#: ../../whatsnew/2.4.rst:609

msgid ""

":class:`Decimal` numbers can be used with the :mod:`math` and :mod:`cmath` "

"modules, but note that they'll be immediately converted to floating-point "

"numbers before the operation is performed, resulting in a possible loss of "

"precision and accuracy. You'll also get back a regular floating-point "

"number and not a :class:`Decimal`. ::"

msgstr ""

#: ../../whatsnew/2.4.rst:622

msgid ""

":class:`Decimal` instances have a :meth:`sqrt` method that returns a "

":class:`Decimal`, but if you need other things such as trigonometric "

"functions you'll have to implement them. ::"

msgstr ""

#: ../../whatsnew/2.4.rst:631

msgid "The :class:`Context` type"

msgstr ":class:`Context` 类型"

#: ../../whatsnew/2.4.rst:633

msgid ""

"Instances of the :class:`Context` class encapsulate several settings for "

"decimal operations:"

msgstr ""

#: ../../whatsnew/2.4.rst:636

msgid ":attr:`prec` is the precision, the number of decimal places."

msgstr ""

#: ../../whatsnew/2.4.rst:638

msgid ""

":attr:`rounding` specifies the rounding mode. The :mod:`decimal` module has"

" constants for the various possibilities: :const:`ROUND_DOWN`, "

":const:`ROUND_CEILING`, :const:`ROUND_HALF_EVEN`, and various others."

msgstr ""

#: ../../whatsnew/2.4.rst:642

msgid ""

":attr:`traps` is a dictionary specifying what happens on encountering "

"certain error conditions: either an exception is raised or a value is "

"returned. Some examples of error conditions are division by zero, loss of "

"precision, and overflow."

msgstr ""

#: ../../whatsnew/2.4.rst:647

msgid ""

"There's a thread-local default context available by calling "

":func:`getcontext`; you can change the properties of this context to alter "

"the default precision, rounding, or trap handling. The following example "

"shows the effect of changing the precision of the default context::"

msgstr ""

#: ../../whatsnew/2.4.rst:660

msgid ""

"The default action for error conditions is selectable; the module can either"

" return a special value such as infinity or not-a-number, or exceptions can "

"be raised::"

msgstr ""

#: ../../whatsnew/2.4.rst:673

msgid ""

"The :class:`Context` instance also has various methods for formatting "

"numbers such as :meth:`to_eng_string` and :meth:`to_sci_string`."

msgstr ""

#: ../../whatsnew/2.4.rst:676

msgid ""

"For more information, see the documentation for the :mod:`decimal` module, "

"which includes a quick-start tutorial and a reference."

msgstr ""

#: ../../whatsnew/2.4.rst:684

msgid ":pep:`327` - Decimal Data Type"

msgstr ":pep:`327` - 十进数据类型"

#: ../../whatsnew/2.4.rst:683

msgid ""

"Written by Facundo Batista and implemented by Facundo Batista, Eric Price, "

"Raymond Hettinger, Aahz, and Tim Peters."

msgstr ""

"由 Facundo Batista 撰写，由Facundo Batista, Eric Price, Raymond Hettinger, Aahz 和"

" Tim Peters 实现。"

#: ../../whatsnew/2.4.rst:688

msgid "http://www.lahey.com/float.htm"

msgstr "http://www.lahey.com/float.htm"

#: ../../whatsnew/2.4.rst:687

msgid ""

"The article uses Fortran code to illustrate many of the problems that "

"floating-point inaccuracy can cause."

msgstr ""

#: ../../whatsnew/2.4.rst:692

msgid "http://speleotrove.com/decimal/"

msgstr "http://speleotrove.com/decimal/"

#: ../../whatsnew/2.4.rst:691

msgid ""

"A description of a decimal-based representation. This representation is "

"being proposed as a standard, and underlies the new Python decimal type. "

"Much of this material was written by Mike Cowlishaw, designer of the Rexx "

"language."

msgstr ""

#: ../../whatsnew/2.4.rst:699

msgid "PEP 328: Multi-line Imports"

msgstr "PEP 328: 多行导入"

#: ../../whatsnew/2.4.rst:701

msgid ""

"One language change is a small syntactic tweak aimed at making it easier to "

"import many names from a module. In a ``from module import names`` "

"statement, *names* is a sequence of names separated by commas. If the "

"sequence is very long, you can either write multiple imports from the same "

"module, or you can use backslashes to escape the line endings like this::"

msgstr ""

#: ../../whatsnew/2.4.rst:712

msgid ""

"The syntactic change in Python 2.4 simply allows putting the names within "

"parentheses. Python ignores newlines within a parenthesized expression, so "

"the backslashes are no longer needed::"

msgstr ""

#: ../../whatsnew/2.4.rst:721

msgid ""

"The PEP also proposes that all :keyword:`import` statements be absolute "

"imports, with a leading ``.`` character to indicate a relative import. This"

" part of the PEP was not implemented for Python 2.4, but was completed for "

"Python 2.5."

msgstr ""

#: ../../whatsnew/2.4.rst:728

msgid ":pep:`328` - Imports: Multi-Line and Absolute/Relative"

msgstr ":pep:`328` - 导入：多行和绝对/相对导入"

#: ../../whatsnew/2.4.rst:729

msgid "Written by Aahz. Multi-line imports were implemented by Dima Dorfman."

msgstr "由 Aahz 撰写，多行导入由 Dima Dorfman 实现。"

#: ../../whatsnew/2.4.rst:735

msgid "PEP 331: Locale-Independent Float/String Conversions"

msgstr ""

#: ../../whatsnew/2.4.rst:737

msgid ""

"The :mod:`locale` modules lets Python software select various conversions "

"and display conventions that are localized to a particular country or "

"language. However, the module was careful to not change the numeric locale "

"because various functions in Python's implementation required that the "

"numeric locale remain set to the ``'C'`` locale. Often this was because the"

" code was using the C library's :c:func:`atof` function."

msgstr ""

#: ../../whatsnew/2.4.rst:744

msgid ""

"Not setting the numeric locale caused trouble for extensions that used "

"third-party C libraries, however, because they wouldn't have the correct "

"locale set. The motivating example was GTK+, whose user interface widgets "

"weren't displaying numbers in the current locale."

msgstr ""

#: ../../whatsnew/2.4.rst:749

msgid ""

"The solution described in the PEP is to add three new functions to the "

"Python API that perform ASCII-only conversions, ignoring the locale setting:"

msgstr ""

#: ../../whatsnew/2.4.rst:752

msgid ""

"``PyOS_ascii_strtod(str, ptr)`` and ``PyOS_ascii_atof(str, ptr)`` both "

"convert a string to a C :c:type:`double`."

msgstr ""

#: ../../whatsnew/2.4.rst:755

msgid ""

"``PyOS_ascii_formatd(buffer, buf_len, format, d)`` converts a "

":c:type:`double` to an ASCII string."

msgstr ""

#: ../../whatsnew/2.4.rst:758

msgid ""

"The code for these functions came from the GLib library "

"(https://developer.gnome.org/glib/stable/), whose developers kindly "

"relicensed the relevant functions and donated them to the Python Software "

"Foundation. The :mod:`locale` module can now change the numeric locale, "

"letting extensions such as GTK+ produce the correct results."

msgstr ""

#: ../../whatsnew/2.4.rst:767

msgid ":pep:`331` - Locale-Independent Float/String Conversions"

msgstr ""

#: ../../whatsnew/2.4.rst:768

msgid "Written by Christian R. Reis, and implemented by Gustavo Carneiro."

msgstr "由Christian R. Reis撰写，由 Gustavo Carneiro 实现。"

#: ../../whatsnew/2.4.rst:774

msgid "Other Language Changes"

msgstr "其他语言特性修改"

#: ../../whatsnew/2.4.rst:776

msgid ""

"Here are all of the changes that Python 2.4 makes to the core Python "

"language."

msgstr "以下是 Python 2.4 针对核心 Python 语言的所有改变。"

#: ../../whatsnew/2.4.rst:778

msgid "Decorators for functions and methods were added (:pep:`318`)."

msgstr "增加了用于函数和方法的装饰器 (:pep:`318`)。"

#: ../../whatsnew/2.4.rst:780

msgid ""

"Built-in :func:`set` and :func:`frozenset` types were added (:pep:`218`). "

"Other new built-ins include the ``reversed(seq)`` function (:pep:`322`)."

msgstr ""

#: ../../whatsnew/2.4.rst:783

msgid "Generator expressions were added (:pep:`289`)."

msgstr ""

#: ../../whatsnew/2.4.rst:785

msgid ""

"Certain numeric expressions no longer return values restricted to 32 or 64 "

"bits (:pep:`237`)."

msgstr ""

#: ../../whatsnew/2.4.rst:788

msgid ""

"You can now put parentheses around the list of names in a ``from module "

"import names`` statement (:pep:`328`)."

msgstr ""

#: ../../whatsnew/2.4.rst:791

msgid ""

"The :meth:`dict.update` method now accepts the same argument forms as the "

":class:`dict` constructor. This includes any mapping, any iterable of "

"key/value pairs, and keyword arguments. (Contributed by Raymond Hettinger.)"

msgstr ""

#: ../../whatsnew/2.4.rst:795

msgid ""

"The string methods :meth:`ljust`, :meth:`rjust`, and :meth:`center` now take"

" an optional argument for specifying a fill character other than a space. "

"(Contributed by Raymond Hettinger.)"

msgstr ""

#: ../../whatsnew/2.4.rst:799

msgid ""

"Strings also gained an :meth:`rsplit` method that works like the "

":meth:`split` method but splits from the end of the string. (Contributed "

"by Sean Reifschneider.) ::"

msgstr ""

#: ../../whatsnew/2.4.rst:808

msgid ""

"Three keyword parameters, *cmp*, *key*, and *reverse*, were added to the "

":meth:`sort` method of lists. These parameters make some common usages of "

":meth:`sort` simpler. All of these parameters are optional."

msgstr ""

#: ../../whatsnew/2.4.rst:812

msgid ""

"For the *cmp* parameter, the value should be a comparison function that "

"takes two parameters and returns -1, 0, or +1 depending on how the "

"parameters compare. This function will then be used to sort the list. "

"Previously this was the only parameter that could be provided to "

":meth:`sort`."

msgstr ""

#: ../../whatsnew/2.4.rst:817

msgid ""

"*key* should be a single-parameter function that takes a list element and "

"returns a comparison key for the element. The list is then sorted using the"

" comparison keys. The following example sorts a list case-insensitively::"

msgstr ""

#: ../../whatsnew/2.4.rst:834

msgid ""

"The last example, which uses the *cmp* parameter, is the old way to perform "

"a case-insensitive sort. It works but is slower than using a *key* "

"parameter. Using *key* calls :meth:`lower` method once for each element in "

"the list while using *cmp* will call it twice for each comparison, so using "

"*key* saves on invocations of the :meth:`lower` method."

msgstr ""

#: ../../whatsnew/2.4.rst:840

msgid ""

"For simple key functions and comparison functions, it is often possible to "

"avoid a :keyword:`lambda` expression by using an unbound method instead. "

"For example, the above case-insensitive sort is best written as::"

msgstr ""

#: ../../whatsnew/2.4.rst:848

msgid ""

"Finally, the *reverse* parameter takes a Boolean value. If the value is "

"true, the list will be sorted into reverse order. Instead of ``L.sort(); "

"L.reverse()``, you can now write ``L.sort(reverse=True)``."

msgstr ""

#: ../../whatsnew/2.4.rst:852

msgid ""

"The results of sorting are now guaranteed to be stable. This means that two"

" entries with equal keys will be returned in the same order as they were "

"input. For example, you can sort a list of people by name, and then sort the"

" list by age, resulting in a list sorted by age where people with the same "

"age are in name-sorted order."

msgstr ""

#: ../../whatsnew/2.4.rst:858