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# Python Documentation Turkish Translation
# Copyright (C) 2001-2023, Python Software Foundation
# This file is distributed under the same license as the Python package.
"Project-Id-Version: Python 3.12\n"
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#: library/contextlib.rst:2
":mod:`!contextlib` --- Utilities for :keyword:`!with`\\ -statement contexts"
#: library/contextlib.rst:7
msgid "**Source code:** :source:`Lib/contextlib.py`"
#: library/contextlib.rst:11
"This module provides utilities for common tasks involving the :keyword:"
"`with` statement. For more information see also :ref:`typecontextmanager` "
"and :ref:`context-managers`."
#: library/contextlib.rst:17
msgid "Utilities"
#: library/contextlib.rst:19
msgid "Functions and classes provided:"
#: library/contextlib.rst:23
"An :term:`abstract base class` for classes that implement :meth:`object."
"__enter__` and :meth:`object.__exit__`. A default implementation for :meth:"
"`object.__enter__` is provided which returns ``self`` while :meth:`object."
"__exit__` is an abstract method which by default returns ``None``. See also "
"the definition of :ref:`typecontextmanager`."
#: library/contextlib.rst:34
"An :term:`abstract base class` for classes that implement :meth:`object."
"__aenter__` and :meth:`object.__aexit__`. A default implementation for :meth:"
"`object.__aenter__` is provided which returns ``self`` while :meth:`object."
"__aexit__` is an abstract method which by default returns ``None``. See also "
"the definition of :ref:`async-context-managers`."
#: library/contextlib.rst:46
"This function is a :term:`decorator` that can be used to define a factory "
"function for :keyword:`with` statement context managers, without needing to "
"create a class or separate :meth:`~object.__enter__` and :meth:`~object."
"__exit__` methods."
#: library/contextlib.rst:50
"While many objects natively support use in with statements, sometimes a "
"resource needs to be managed that isn't a context manager in its own right, "
"and doesn't implement a ``close()`` method for use with ``contextlib."
"closing``"
#: library/contextlib.rst:54
"An abstract example would be the following to ensure correct resource "
"management::"
#: library/contextlib.rst:69
msgid "The function can then be used like this::"
#: library/contextlib.rst:75
"The function being decorated must return a :term:`generator`-iterator when "
"called. This iterator must yield exactly one value, which will be bound to "
"the targets in the :keyword:`with` statement's :keyword:`!as` clause, if any."
#: library/contextlib.rst:79
"At the point where the generator yields, the block nested in the :keyword:"
"`with` statement is executed.  The generator is then resumed after the block "
"is exited. If an unhandled exception occurs in the block, it is reraised "
"inside the generator at the point where the yield occurred.  Thus, you can "
"use a :keyword:`try`...\\ :keyword:`except`...\\ :keyword:`finally` "
"statement to trap the error (if any), or ensure that some cleanup takes "
"place. If an exception is trapped merely in order to log it or to perform "
"some action (rather than to suppress it entirely), the generator must "
"reraise that exception. Otherwise the generator context manager will "
"indicate to the :keyword:`!with` statement that the exception has been "
"handled, and execution will resume with the statement immediately following "
"the :keyword:`!with` statement."
#: library/contextlib.rst:91
":func:`contextmanager` uses :class:`ContextDecorator` so the context "
"managers it creates can be used as decorators as well as in :keyword:`with` "
"statements. When used as a decorator, a new generator instance is implicitly "
"created on each function call (this allows the otherwise \"one-shot\" "
"context managers created by :func:`contextmanager` to meet the requirement "
"that context managers support multiple invocations in order to be used as "
"decorators)."
#: library/contextlib.rst:98
msgid "Use of :class:`ContextDecorator`."
#: library/contextlib.rst:104
"Similar to :func:`~contextlib.contextmanager`, but creates an :ref:"
"`asynchronous context manager <async-context-managers>`."
#: library/contextlib.rst:107
"This function is a :term:`decorator` that can be used to define a factory "
"function for :keyword:`async with` statement asynchronous context managers, "
"without needing to create a class or separate :meth:`__aenter__` and :meth:"
"`__aexit__` methods. It must be applied to an :term:`asynchronous generator` "
"function."
#: library/contextlib.rst:113
msgid "A simple example::"
#: library/contextlib.rst:131
"Context managers defined with :func:`asynccontextmanager` can be used either "
"as decorators or with :keyword:`async with` statements::"
#: library/contextlib.rst:149
"When used as a decorator, a new generator instance is implicitly created on "
"each function call. This allows the otherwise \"one-shot\" context managers "
"created by :func:`asynccontextmanager` to meet the requirement that context "
"managers support multiple invocations in order to be used as decorators."
#: library/contextlib.rst:154
"Async context managers created with :func:`asynccontextmanager` can be used "
"as decorators."
#: library/contextlib.rst:161
"Return a context manager that closes *thing* upon completion of the block.  "
"This is basically equivalent to::"
#: library/contextlib.rst:173
msgid "And lets you write code like this::"
#: library/contextlib.rst:182
"without needing to explicitly close ``page``.  Even if an error occurs, "
"``page.close()`` will be called when the :keyword:`with` block is exited."
#: library/contextlib.rst:188
"Return an async context manager that calls the ``aclose()`` method of "
"*thing* upon completion of the block.  This is basically equivalent to::"
#: library/contextlib.rst:200
"Significantly, ``aclosing()`` supports deterministic cleanup of async "
"generators when they happen to exit early by :keyword:`break` or an "
"exception.  For example::"
#: library/contextlib.rst:211
"This pattern ensures that the generator's async exit code is executed in the "
"same context as its iterations (so that exceptions and context variables "
"work as expected, and the exit code isn't run after the lifetime of some "
"task it depends on)."
#: library/contextlib.rst:223
"Return a context manager that returns *enter_result* from ``__enter__``, but "
"otherwise does nothing. It is intended to be used as a stand-in for an "
"optional context manager, for example::"
#: library/contextlib.rst:237
msgid "An example using *enter_result*::"
#: library/contextlib.rst:250
"It can also be used as a stand-in for :ref:`asynchronous context managers "
"<async-context-managers>`::"
#: library/contextlib.rst:266
msgid ":term:`asynchronous context manager` support was added."
#: library/contextlib.rst:273
"Return a context manager that suppresses any of the specified exceptions if "
"they occur in the body of a :keyword:`!with` statement and then resumes "
"execution with the first statement following the end of the :keyword:`!with` "
"statement."
#: library/contextlib.rst:278
"As with any other mechanism that completely suppresses exceptions, this "
"context manager should be used only to cover very specific errors where "
"silently continuing with program execution is known to be the right thing to "
#: library/contextlib.rst:283
msgid "For example::"
#: library/contextlib.rst:293
msgid "This code is equivalent to::"
#: library/contextlib.rst:352 library/contextlib.rst:379
msgid "This context manager is :ref:`reentrant <reentrant-cms>`."
#: library/contextlib.rst:307
"If the code within the :keyword:`!with` block raises a :exc:"
"`BaseExceptionGroup`, suppressed exceptions are removed from the group.  If "
"any exceptions in the group are not suppressed, a group containing them is "
"re-raised."
#: library/contextlib.rst:313
"``suppress`` now supports suppressing exceptions raised as part of an :exc:"
"`BaseExceptionGroup`."
#: library/contextlib.rst:319
"Context manager for temporarily redirecting :data:`sys.stdout` to another "
"file or file-like object."
#: library/contextlib.rst:322
"This tool adds flexibility to existing functions or classes whose output is "
"hardwired to stdout."
#: library/contextlib.rst:325
"For example, the output of :func:`help` normally is sent to *sys.stdout*. "
"You can capture that output in a string by redirecting the output to an :"
"class:`io.StringIO` object. The replacement stream is returned from the "
"``__enter__`` method and so is available as the target of the :keyword:"
"`with` statement::"
#: library/contextlib.rst:335
"To send the output of :func:`help` to a file on disk, redirect the output to "
"a regular file::"
#: library/contextlib.rst:342
msgid "To send the output of :func:`help` to *sys.stderr*::"
#: library/contextlib.rst:347
"Note that the global side effect on :data:`sys.stdout` means that this "
"context manager is not suitable for use in library code and most threaded "
"applications. It also has no effect on the output of subprocesses. However, "
"it is still a useful approach for many utility scripts."
#: library/contextlib.rst:359
"Similar to :func:`~contextlib.redirect_stdout` but redirecting :data:`sys."
"stderr` to another file or file-like object."
#: library/contextlib.rst:369
"Non parallel-safe context manager to change the current working directory. "
"As this changes a global state, the working directory, it is not suitable "
"for use in most threaded or async contexts. It is also not suitable for most "
"non-linear code execution, like generators, where the program execution is "
"temporarily relinquished -- unless explicitly desired, you should not yield "
"when this context manager is active."
#: library/contextlib.rst:376
"This is a simple wrapper around :func:`~os.chdir`, it changes the current "
"working directory upon entering and restores the old one on exit."
#: library/contextlib.rst:386
"A base class that enables a context manager to also be used as a decorator."
#: library/contextlib.rst:388
"Context managers inheriting from ``ContextDecorator`` have to implement "
"``__enter__`` and ``__exit__`` as normal. ``__exit__`` retains its optional "
"exception handling even when used as a decorator."
#: library/contextlib.rst:392
"``ContextDecorator`` is used by :func:`contextmanager`, so you get this "
"functionality automatically."
#: library/contextlib.rst:395
msgid "Example of ``ContextDecorator``::"
#: library/contextlib.rst:480
msgid "The class can then be used like this::"
#: library/contextlib.rst:426
"This change is just syntactic sugar for any construct of the following form::"
#: library/contextlib.rst:432
msgid "``ContextDecorator`` lets you instead write::"
#: library/contextlib.rst:438
"It makes it clear that the ``cm`` applies to the whole function, rather than "
"just a piece of it (and saving an indentation level is nice, too)."
#: library/contextlib.rst:441
"Existing context managers that already have a base class can be extended by "
"using ``ContextDecorator`` as a mixin class::"
#: library/contextlib.rst:454
"As the decorated function must be able to be called multiple times, the "
"underlying context manager must support use in multiple :keyword:`with` "
"statements. If this is not the case, then the original construct with the "
"explicit :keyword:`!with` statement inside the function should be used."
#: library/contextlib.rst:464
"Similar to :class:`ContextDecorator` but only for asynchronous functions."
#: library/contextlib.rst:466
msgid "Example of ``AsyncContextDecorator``::"
#: library/contextlib.rst:505
"A context manager that is designed to make it easy to programmatically "
"combine other context managers and cleanup functions, especially those that "
"are optional or otherwise driven by input data."
#: library/contextlib.rst:509
"For example, a set of files may easily be handled in a single with statement "
"as follows::"
#: library/contextlib.rst:518
"The :meth:`~object.__enter__` method returns the :class:`ExitStack` "
"instance, and performs no additional operations."
#: library/contextlib.rst:521
"Each instance maintains a stack of registered callbacks that are called in "
"reverse order when the instance is closed (either explicitly or implicitly "
"at the end of a :keyword:`with` statement). Note that callbacks are *not* "
"invoked implicitly when the context stack instance is garbage collected."
#: library/contextlib.rst:526
"This stack model is used so that context managers that acquire their "
"resources in their ``__init__`` method (such as file objects) can be handled "
"correctly."
#: library/contextlib.rst:530
"Since registered callbacks are invoked in the reverse order of registration, "
"this ends up behaving as if multiple nested :keyword:`with` statements had "
"been used with the registered set of callbacks. This even extends to "
"exception handling - if an inner callback suppresses or replaces an "
"exception, then outer callbacks will be passed arguments based on that "
"updated state."
#: library/contextlib.rst:537
"This is a relatively low level API that takes care of the details of "
"correctly unwinding the stack of exit callbacks. It provides a suitable "
"foundation for higher level context managers that manipulate the exit stack "
"in application specific ways."
#: library/contextlib.rst:546
"Enters a new context manager and adds its :meth:`~object.__exit__` method to "
"the callback stack. The return value is the result of the context manager's "
"own :meth:`~object.__enter__` method."
#: library/contextlib.rst:550
"These context managers may suppress exceptions just as they normally would "
"if used directly as part of a :keyword:`with` statement."
#: library/contextlib.rst:553
"Raises :exc:`TypeError` instead of :exc:`AttributeError` if *cm* is not a "
"context manager."
#: library/contextlib.rst:559
"Adds a context manager's :meth:`~object.__exit__` method to the callback "
#: library/contextlib.rst:561
"As ``__enter__`` is *not* invoked, this method can be used to cover part of "
"an :meth:`~object.__enter__` implementation with a context manager's own :"
"meth:`~object.__exit__` method."
#: library/contextlib.rst:565
"If passed an object that is not a context manager, this method assumes it is "
"a callback with the same signature as a context manager's :meth:`~object."
"__exit__` method and adds it directly to the callback stack."
#: library/contextlib.rst:569
"By returning true values, these callbacks can suppress exceptions the same "
"way context manager :meth:`~object.__exit__` methods can."
#: library/contextlib.rst:572
"The passed in object is returned from the function, allowing this method to "
"be used as a function decorator."
#: library/contextlib.rst:577
"Accepts an arbitrary callback function and arguments and adds it to the "
"callback stack."
#: library/contextlib.rst:580
"Unlike the other methods, callbacks added this way cannot suppress "
"exceptions (as they are never passed the exception details)."
#: library/contextlib.rst:583
"The passed in callback is returned from the function, allowing this method "
"to be used as a function decorator."
#: library/contextlib.rst:588
"Transfers the callback stack to a fresh :class:`ExitStack` instance and "
"returns it. No callbacks are invoked by this operation - instead, they will "
"now be invoked when the new stack is closed (either explicitly or implicitly "
"at the end of a :keyword:`with` statement)."
#: library/contextlib.rst:593
"For example, a group of files can be opened as an \"all or nothing\" "
"operation as follows::"
#: library/contextlib.rst:607
"Immediately unwinds the callback stack, invoking callbacks in the reverse "
"order of registration. For any context managers and exit callbacks "
"registered, the arguments passed in will indicate that no exception occurred."
#: library/contextlib.rst:614
"An :ref:`asynchronous context manager <async-context-managers>`, similar to :"
"class:`ExitStack`, that supports combining both synchronous and asynchronous "
"context managers, as well as having coroutines for cleanup logic."
#: library/contextlib.rst:619
"The :meth:`close` method is not implemented, :meth:`aclose` must be used "
#: library/contextlib.rst:624
"Similar to :meth:`enter_context` but expects an asynchronous context manager."
#: library/contextlib.rst:627
"Raises :exc:`TypeError` instead of :exc:`AttributeError` if *cm* is not an "
"asynchronous context manager."
#: library/contextlib.rst:633
"Similar to :meth:`push` but expects either an asynchronous context manager "
"or a coroutine function."
#: library/contextlib.rst:638
msgid "Similar to :meth:`callback` but expects a coroutine function."
#: library/contextlib.rst:642
msgid "Similar to :meth:`close` but properly handles awaitables."
#: library/contextlib.rst:644
msgid "Continuing the example for :func:`asynccontextmanager`::"
#: library/contextlib.rst:656
msgid "Examples and Recipes"
#: library/contextlib.rst:658
"This section describes some examples and recipes for making effective use of "
"the tools provided by :mod:`contextlib`."
#: library/contextlib.rst:663
msgid "Supporting a variable number of context managers"
#: library/contextlib.rst:665
"The primary use case for :class:`ExitStack` is the one given in the class "
"documentation: supporting a variable number of context managers and other "
"cleanup operations in a single :keyword:`with` statement. The variability "
"may come from the number of context managers needed being driven by user "
"input (such as opening a user specified collection of files), or from some "
"of the context managers being optional::"
#: library/contextlib.rst:680
"As shown, :class:`ExitStack` also makes it quite easy to use :keyword:`with` "
"statements to manage arbitrary resources that don't natively support the "
"context management protocol."
#: library/contextlib.rst:686
msgid "Catching exceptions from ``__enter__`` methods"
#: library/contextlib.rst:688
"It is occasionally desirable to catch exceptions from an ``__enter__`` "
"method implementation, *without* inadvertently catching exceptions from the :"
"keyword:`with` statement body or the context manager's ``__exit__`` method. "
"By using :class:`ExitStack` the steps in the context management protocol can "
"be separated slightly in order to allow this::"
#: library/contextlib.rst:703
"Actually needing to do this is likely to indicate that the underlying API "
"should be providing a direct resource management interface for use with :"
"keyword:`try`/:keyword:`except`/:keyword:`finally` statements, but not all "
"APIs are well designed in that regard. When a context manager is the only "
"resource management API provided, then :class:`ExitStack` can make it easier "
"to handle various situations that can't be handled directly in a :keyword:"
"`with` statement."
#: library/contextlib.rst:713
msgid "Cleaning up in an ``__enter__`` implementation"
#: library/contextlib.rst:715
"As noted in the documentation of :meth:`ExitStack.push`, this method can be "
"useful in cleaning up an already allocated resource if later steps in the :"
"meth:`~object.__enter__` implementation fail."
#: library/contextlib.rst:719
"Here's an example of doing this for a context manager that accepts resource "
"acquisition and release functions, along with an optional validation "
"function, and maps them to the context management protocol::"
#: library/contextlib.rst:759
msgid "Replacing any use of ``try-finally`` and flag variables"
#: library/contextlib.rst:761
"A pattern you will sometimes see is a ``try-finally`` statement with a flag "
"variable to indicate whether or not the body of the ``finally`` clause "
"should be executed. In its simplest form (that can't already be handled just "
"by using an ``except`` clause instead), it looks something like this::"
#: library/contextlib.rst:775
"As with any ``try`` statement based code, this can cause problems for "
"development and review, because the setup code and the cleanup code can end "
"up being separated by arbitrarily long sections of code."
#: library/contextlib.rst:779
":class:`ExitStack` makes it possible to instead register a callback for "
"execution at the end of a ``with`` statement, and then later decide to skip "
"executing that callback::"
#: library/contextlib.rst:791
"This allows the intended cleanup up behaviour to be made explicit up front, "
"rather than requiring a separate flag variable."
#: library/contextlib.rst:794
"If a particular application uses this pattern a lot, it can be simplified "
"even further by means of a small helper class::"
#: library/contextlib.rst:812
"If the resource cleanup isn't already neatly bundled into a standalone "
"function, then it is still possible to use the decorator form of :meth:"
"`ExitStack.callback` to declare the resource cleanup in advance::"
#: library/contextlib.rst:827
"Due to the way the decorator protocol works, a callback function declared "
"this way cannot take any parameters. Instead, any resources to be released "
"must be accessed as closure variables."
#: library/contextlib.rst:833
msgid "Using a context manager as a function decorator"
#: library/contextlib.rst:835
":class:`ContextDecorator` makes it possible to use a context manager in both "
"an ordinary ``with`` statement and also as a function decorator."
#: library/contextlib.rst:838
"For example, it is sometimes useful to wrap functions or groups of "
"statements with a logger that can track the time of entry and time of exit.  "
"Rather than writing both a function decorator and a context manager for the "
"task, inheriting from :class:`ContextDecorator` provides both capabilities "
"in a single definition::"
#: library/contextlib.rst:859
msgid "Instances of this class can be used as both a context manager::"
#: library/contextlib.rst:865
msgid "And also as a function decorator::"
#: library/contextlib.rst:872
"Note that there is one additional limitation when using context managers as "
"function decorators: there's no way to access the return value of :meth:"
"`~object.__enter__`. If that value is needed, then it is still necessary to "
"use an explicit ``with`` statement."
#: library/contextlib.rst:880
msgid ":pep:`343` - The \"with\" statement"
#: library/contextlib.rst:880
"The specification, background, and examples for the Python :keyword:`with` "
"statement."
#: library/contextlib.rst:886
msgid "Single use, reusable and reentrant context managers"
#: library/contextlib.rst:888
"Most context managers are written in a way that means they can only be used "
"effectively in a :keyword:`with` statement once. These single use context "
"managers must be created afresh each time they're used - attempting to use "
"them a second time will trigger an exception or otherwise not work correctly."
#: library/contextlib.rst:894
"This common limitation means that it is generally advisable to create "
"context managers directly in the header of the :keyword:`with` statement "
"where they are used (as shown in all of the usage examples above)."
#: library/contextlib.rst:898
"Files are an example of effectively single use context managers, since the "
"first :keyword:`with` statement will close the file, preventing any further "
"IO operations using that file object."
#: library/contextlib.rst:902
"Context managers created using :func:`contextmanager` are also single use "
"context managers, and will complain about the underlying generator failing "
"to yield if an attempt is made to use them a second time::"
#: library/contextlib.rst:930
msgid "Reentrant context managers"
#: library/contextlib.rst:932
"More sophisticated context managers may be \"reentrant\". These context "
"managers can not only be used in multiple :keyword:`with` statements, but "
"may also be used *inside* a :keyword:`!with` statement that is already using "
"the same context manager."
#: library/contextlib.rst:937
":class:`threading.RLock` is an example of a reentrant context manager, as "
"are :func:`suppress`, :func:`redirect_stdout`, and :func:`chdir`. Here's a "
"very simple example of reentrant use::"
#: library/contextlib.rst:956
"Real world examples of reentrancy are more likely to involve multiple "
"functions calling each other and hence be far more complicated than this "
#: library/contextlib.rst:960
"Note also that being reentrant is *not* the same thing as being thread "
"safe. :func:`redirect_stdout`, for example, is definitely not thread safe, "
"as it makes a global modification to the system state by binding :data:`sys."
"stdout` to a different stream."
#: library/contextlib.rst:969
msgid "Reusable context managers"
#: library/contextlib.rst:971
"Distinct from both single use and reentrant context managers are "
"\"reusable\" context managers (or, to be completely explicit, \"reusable, "
"but not reentrant\" context managers, since reentrant context managers are "
"also reusable). These context managers support being used multiple times, "
"but will fail (or otherwise not work correctly) if the specific context "
"manager instance has already been used in a containing with statement."
#: library/contextlib.rst:978
":class:`threading.Lock` is an example of a reusable, but not reentrant, "
"context manager (for a reentrant lock, it is necessary to use :class:"
"`threading.RLock` instead)."
#: library/contextlib.rst:982
"Another example of a reusable, but not reentrant, context manager is :class:"
"`ExitStack`, as it invokes *all* currently registered callbacks when leaving "
"any with statement, regardless of where those callbacks were added::"
#: library/contextlib.rst:1013
"As the output from the example shows, reusing a single stack object across "
"multiple with statements works correctly, but attempting to nest them will "
"cause the stack to be cleared at the end of the innermost with statement, "
"which is unlikely to be desirable behaviour."
#: library/contextlib.rst:1018
"Using separate :class:`ExitStack` instances instead of reusing a single "
"instance avoids that problem::"
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