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# 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:
# Claudio Rogerio Carvalho Filho <excriptbrasil@gmail.com>, 2020
# Adorilson Bezerra <adorilson@gmail.com>, 2020
# Mariana Costa <mrncstt@gmail.com>, 2020
# Julia Rizza <contato@juliarizza.com>, 2020
# Melissa Weber Mendonça <melissawm@gmail.com>, 2021
# Rafael Fontenelle <rffontenelle@gmail.com>, 2023
#
#, fuzzy
msgid ""
msgstr ""
"Project-Id-Version: Python 3.8\n"
"Report-Msgid-Bugs-To: \n"
"POT-Creation-Date: 2024-08-31 13:50+0000\n"
"PO-Revision-Date: 2020-05-30 11:53+0000\n"
"Last-Translator: Rafael Fontenelle <rffontenelle@gmail.com>, 2023\n"
"Language-Team: Portuguese (Brazil) (https://app.transifex.com/python-doc/"
"teams/5390/pt_BR/)\n"
"Language: pt_BR\n"
"MIME-Version: 1.0\n"
"Content-Type: text/plain; charset=UTF-8\n"
"Content-Transfer-Encoding: 8bit\n"
"Plural-Forms: nplurals=3; plural=(n == 0 || n == 1) ? 0 : n != 0 && n % "
"1000000 == 0 ? 1 : 2;\n"
#: ../../extending/extending.rst:8
msgid "Extending Python with C or C++"
msgstr "Estendendo Python com C ou C++"
#: ../../extending/extending.rst:10
msgid ""
"It is quite easy to add new built-in modules to Python, if you know how to "
"program in C. Such :dfn:`extension modules` can do two things that can't be "
"done directly in Python: they can implement new built-in object types, and "
"they can call C library functions and system calls."
msgstr ""
"É muito fácil adicionar novos módulos embutidos ao Python, se você souber "
"programar em C. Você pode adicionar :dfn:`módulos de extensão` para fazer "
"duas coisas que não podem ser feitas diretamente no Python: eles podem "
"implementar novos nos tipos de objetos embutidos e eles podem chamar funções "
"da biblioteca C e chamadas do sistema."
#: ../../extending/extending.rst:15
msgid ""
"To support extensions, the Python API (Application Programmers Interface) "
"defines a set of functions, macros and variables that provide access to most "
"aspects of the Python run-time system. The Python API is incorporated in a "
"C source file by including the header ``\"Python.h\"``."
msgstr ""
"Para dar suporte a extensões, a API do Python API (Application Programmers "
"Interface) define um conjunto de funções, macros e variáveis que fornecem "
"acesso à maior parte dos aspectos do sistema de tempo de execução do "
"Python. A API do Python pode ser incorporada em um arquivo fonte em C com a "
"inclusão do cabeçalho ``\"Python.h\"``."
#: ../../extending/extending.rst:20
msgid ""
"The compilation of an extension module depends on its intended use as well "
"as on your system setup; details are given in later chapters."
msgstr ""
"A compilação de um módulo de extensão depende do uso pretendido e da "
"configuração do sistema; detalhes serão dados nos próximos capítulos."
#: ../../extending/extending.rst:25
msgid ""
"The C extension interface is specific to CPython, and extension modules do "
"not work on other Python implementations. In many cases, it is possible to "
"avoid writing C extensions and preserve portability to other "
"implementations. For example, if your use case is calling C library "
"functions or system calls, you should consider using the :mod:`ctypes` "
"module or the `cffi <https://cffi.readthedocs.io/>`_ library rather than "
"writing custom C code. These modules let you write Python code to interface "
"with C code and are more portable between implementations of Python than "
"writing and compiling a C extension module."
msgstr ""
"A interface de extensões em C é específica para o CPython, e módulos de "
"extensão não funcionam em outras implementações do Python. Em muitos casos, "
"é possível evitar a criação destas extensões em C e preservar a "
"portabilidade para outras implementações. Por exemplo, se o seu caso de uso "
"for o de fazer chamadas a funções em bibliotecas C ou chamadas de sistema, "
"considere utilizar o módulo :mod:`ctypes` ou a biblioteca `cffi <https://"
"cffi.readthedocs.io/>`_ ao invés de escrever código C personalizado. Esses "
"módulos permitem escrever código Python que pode interoperar com código C e "
"que é mais portável entre implementações do Python do que escrever e "
"compilar um módulo de extensão em C."
#: ../../extending/extending.rst:40
msgid "A Simple Example"
msgstr "Um Exemplo Simples"
#: ../../extending/extending.rst:42
msgid ""
"Let's create an extension module called ``spam`` (the favorite food of Monty "
"Python fans...) and let's say we want to create a Python interface to the C "
"library function :c:func:`system` [#]_. This function takes a null-"
"terminated character string as argument and returns an integer. We want "
"this function to be callable from Python as follows:"
msgstr ""
"Vamos criar um módulo de extensão chamado ``spam`` (a comida favorita dos "
"fãs de Monty Python...) e digamos que nosso objetivo seja criar uma "
"interface em Python para a função da biblioteca C :c:func:`system` [#]_. "
"Essa função toma uma string de caracteres terminada em nulo como argumento e "
"retorna um número inteiro. Queremos que essa função seja chamável a partir "
"do Python como abaixo:"
#: ../../extending/extending.rst:53
msgid ""
"Begin by creating a file :file:`spammodule.c`. (Historically, if a module "
"is called ``spam``, the C file containing its implementation is "
"called :file:`spammodule.c`; if the module name is very long, like "
"``spammify``, the module name can be just :file:`spammify.c`.)"
msgstr ""
"Comece criando um arquivo chamado :file:`spammodule.c`. (Historicamente, se "
"um módulo for chamado ``spam``, o arquivo C contendo sua implementação é "
"chamado :file:`spammodule.c`; se o nome do módulo for muito longo, como "
"``spammify``, o nome do arquivo pode ser só :file:`spammify.c`.)"
#: ../../extending/extending.rst:58
msgid "The first two lines of our file can be::"
msgstr "As duas primeiras linhas do nosso arquivo podem ser::"
#: ../../extending/extending.rst:63
msgid ""
"which pulls in the Python API (you can add a comment describing the purpose "
"of the module and a copyright notice if you like)."
msgstr ""
"o que carrega a API do Python (você pode adicionar um comentário descrevendo "
"o propósito do módulo e uma nota de copyright, se desejar)."
#: ../../extending/extending.rst:68
msgid ""
"Since Python may define some pre-processor definitions which affect the "
"standard headers on some systems, you *must* include :file:`Python.h` before "
"any standard headers are included."
msgstr ""
"Uma vez que Python pode definir algumas definições de pré-processador que "
"afetam os cabeçalhos padrão em alguns sistemas, você *deve* "
"incluir :file:`Python.h` antes de quaisquer cabeçalhos padrão serem "
"incluídos."
#: ../../extending/extending.rst:72
msgid ""
"It is recommended to always define ``PY_SSIZE_T_CLEAN`` before including "
"``Python.h``. See :ref:`parsetuple` for a description of this macro."
msgstr ""
"É recomendado sempre definir ``PY_SSIZE_T_CLEAN`` antes de incluir "
"``Python.h``. Veja :ref:`parsetuple` para uma descrição desse macro."
#: ../../extending/extending.rst:75
msgid ""
"All user-visible symbols defined by :file:`Python.h` have a prefix of ``Py`` "
"or ``PY``, except those defined in standard header files. For convenience, "
"and since they are used extensively by the Python interpreter, "
"``\"Python.h\"`` includes a few standard header files: ``<stdio.h>``, "
"``<string.h>``, ``<errno.h>``, and ``<stdlib.h>``. If the latter header "
"file does not exist on your system, it declares the "
"functions :c:func:`malloc`, :c:func:`free` and :c:func:`realloc` directly."
msgstr ""
#: ../../extending/extending.rst:83
msgid ""
"The next thing we add to our module file is the C function that will be "
"called when the Python expression ``spam.system(string)`` is evaluated "
"(we'll see shortly how it ends up being called)::"
msgstr ""
#: ../../extending/extending.rst:99
msgid ""
"There is a straightforward translation from the argument list in Python (for "
"example, the single expression ``\"ls -l\"``) to the arguments passed to the "
"C function. The C function always has two arguments, conventionally named "
"*self* and *args*."
msgstr ""
#: ../../extending/extending.rst:104
msgid ""
"The *self* argument points to the module object for module-level functions; "
"for a method it would point to the object instance."
msgstr ""
#: ../../extending/extending.rst:107
msgid ""
"The *args* argument will be a pointer to a Python tuple object containing "
"the arguments. Each item of the tuple corresponds to an argument in the "
"call's argument list. The arguments are Python objects --- in order to do "
"anything with them in our C function we have to convert them to C values. "
"The function :c:func:`PyArg_ParseTuple` in the Python API checks the "
"argument types and converts them to C values. It uses a template string to "
"determine the required types of the arguments as well as the types of the C "
"variables into which to store the converted values. More about this later."
msgstr ""
#: ../../extending/extending.rst:116
msgid ""
":c:func:`PyArg_ParseTuple` returns true (nonzero) if all arguments have the "
"right type and its components have been stored in the variables whose "
"addresses are passed. It returns false (zero) if an invalid argument list "
"was passed. In the latter case it also raises an appropriate exception so "
"the calling function can return ``NULL`` immediately (as we saw in the "
"example)."
msgstr ""
#: ../../extending/extending.rst:126
msgid "Intermezzo: Errors and Exceptions"
msgstr ""
#: ../../extending/extending.rst:128
msgid ""
"An important convention throughout the Python interpreter is the following: "
"when a function fails, it should set an exception condition and return an "
"error value (usually a ``NULL`` pointer). Exceptions are stored in a static "
"global variable inside the interpreter; if this variable is ``NULL`` no "
"exception has occurred. A second global variable stores the \"associated "
"value\" of the exception (the second argument to :keyword:`raise`). A third "
"variable contains the stack traceback in case the error originated in Python "
"code. These three variables are the C equivalents of the result in Python "
"of :meth:`sys.exc_info` (see the section on module :mod:`sys` in the Python "
"Library Reference). It is important to know about them to understand how "
"errors are passed around."
msgstr ""
#: ../../extending/extending.rst:139
msgid ""
"The Python API defines a number of functions to set various types of "
"exceptions."
msgstr ""
#: ../../extending/extending.rst:141
msgid ""
"The most common one is :c:func:`PyErr_SetString`. Its arguments are an "
"exception object and a C string. The exception object is usually a "
"predefined object like :c:data:`PyExc_ZeroDivisionError`. The C string "
"indicates the cause of the error and is converted to a Python string object "
"and stored as the \"associated value\" of the exception."
msgstr ""
#: ../../extending/extending.rst:147
msgid ""
"Another useful function is :c:func:`PyErr_SetFromErrno`, which only takes an "
"exception argument and constructs the associated value by inspection of the "
"global variable :c:data:`errno`. The most general function "
"is :c:func:`PyErr_SetObject`, which takes two object arguments, the "
"exception and its associated value. You don't need to :c:func:`Py_INCREF` "
"the objects passed to any of these functions."
msgstr ""
#: ../../extending/extending.rst:154
msgid ""
"You can test non-destructively whether an exception has been set "
"with :c:func:`PyErr_Occurred`. This returns the current exception object, "
"or ``NULL`` if no exception has occurred. You normally don't need to "
"call :c:func:`PyErr_Occurred` to see whether an error occurred in a function "
"call, since you should be able to tell from the return value."
msgstr ""
#: ../../extending/extending.rst:160
msgid ""
"When a function *f* that calls another function *g* detects that the latter "
"fails, *f* should itself return an error value (usually ``NULL`` or "
"``-1``). It should *not* call one of the :c:func:`PyErr_\\*` functions --- "
"one has already been called by *g*. *f*'s caller is then supposed to also "
"return an error indication to *its* caller, again *without* "
"calling :c:func:`PyErr_\\*`, and so on --- the most detailed cause of the "
"error was already reported by the function that first detected it. Once the "
"error reaches the Python interpreter's main loop, this aborts the currently "
"executing Python code and tries to find an exception handler specified by "
"the Python programmer."
msgstr ""
#: ../../extending/extending.rst:170
msgid ""
"(There are situations where a module can actually give a more detailed error "
"message by calling another :c:func:`PyErr_\\*` function, and in such cases "
"it is fine to do so. As a general rule, however, this is not necessary, and "
"can cause information about the cause of the error to be lost: most "
"operations can fail for a variety of reasons.)"
msgstr ""
#: ../../extending/extending.rst:176
msgid ""
"To ignore an exception set by a function call that failed, the exception "
"condition must be cleared explicitly by calling :c:func:`PyErr_Clear`. The "
"only time C code should call :c:func:`PyErr_Clear` is if it doesn't want to "
"pass the error on to the interpreter but wants to handle it completely by "
"itself (possibly by trying something else, or pretending nothing went wrong)."
msgstr ""
#: ../../extending/extending.rst:182
msgid ""
"Every failing :c:func:`malloc` call must be turned into an exception --- the "
"direct caller of :c:func:`malloc` (or :c:func:`realloc`) must "
"call :c:func:`PyErr_NoMemory` and return a failure indicator itself. All "
"the object-creating functions (for example, :c:func:`PyLong_FromLong`) "
"already do this, so this note is only relevant to those who "
"call :c:func:`malloc` directly."
msgstr ""
#: ../../extending/extending.rst:188
msgid ""
"Also note that, with the important exception of :c:func:`PyArg_ParseTuple` "
"and friends, functions that return an integer status usually return a "
"positive value or zero for success and ``-1`` for failure, like Unix system "
"calls."
msgstr ""
#: ../../extending/extending.rst:192
msgid ""
"Finally, be careful to clean up garbage (by making :c:func:`Py_XDECREF` "
"or :c:func:`Py_DECREF` calls for objects you have already created) when you "
"return an error indicator!"
msgstr ""
#: ../../extending/extending.rst:196
msgid ""
"The choice of which exception to raise is entirely yours. There are "
"predeclared C objects corresponding to all built-in Python exceptions, such "
"as :c:data:`PyExc_ZeroDivisionError`, which you can use directly. Of course, "
"you should choose exceptions wisely --- don't use :c:data:`PyExc_TypeError` "
"to mean that a file couldn't be opened (that should probably "
"be :c:data:`PyExc_IOError`). If something's wrong with the argument list, "
"the :c:func:`PyArg_ParseTuple` function usually "
"raises :c:data:`PyExc_TypeError`. If you have an argument whose value must "
"be in a particular range or must satisfy other "
"conditions, :c:data:`PyExc_ValueError` is appropriate."
msgstr ""
#: ../../extending/extending.rst:206
msgid ""
"You can also define a new exception that is unique to your module. For this, "
"you usually declare a static object variable at the beginning of your file::"
msgstr ""
#: ../../extending/extending.rst:211
msgid ""
"and initialize it in your module's initialization function "
"(:c:func:`PyInit_spam`) with an exception object::"
msgstr ""
#: ../../extending/extending.rst:235
msgid ""
"Note that the Python name for the exception object is :exc:`spam.error`. "
"The :c:func:`PyErr_NewException` function may create a class with the base "
"class being :exc:`Exception` (unless another class is passed in instead of "
"``NULL``), described in :ref:`bltin-exceptions`."
msgstr ""
#: ../../extending/extending.rst:240
msgid ""
"Note also that the :c:data:`SpamError` variable retains a reference to the "
"newly created exception class; this is intentional! Since the exception "
"could be removed from the module by external code, an owned reference to the "
"class is needed to ensure that it will not be discarded, "
"causing :c:data:`SpamError` to become a dangling pointer. Should it become a "
"dangling pointer, C code which raises the exception could cause a core dump "
"or other unintended side effects."
msgstr ""
#: ../../extending/extending.rst:247
msgid ""
"We discuss the use of ``PyMODINIT_FUNC`` as a function return type later in "
"this sample."
msgstr ""
#: ../../extending/extending.rst:250
msgid ""
"The :exc:`spam.error` exception can be raised in your extension module using "
"a call to :c:func:`PyErr_SetString` as shown below::"
msgstr ""
#: ../../extending/extending.rst:273
msgid "Back to the Example"
msgstr ""
#: ../../extending/extending.rst:275
msgid ""
"Going back to our example function, you should now be able to understand "
"this statement::"
msgstr ""
#: ../../extending/extending.rst:281
msgid ""
"It returns ``NULL`` (the error indicator for functions returning object "
"pointers) if an error is detected in the argument list, relying on the "
"exception set by :c:func:`PyArg_ParseTuple`. Otherwise the string value of "
"the argument has been copied to the local variable :c:data:`command`. This "
"is a pointer assignment and you are not supposed to modify the string to "
"which it points (so in Standard C, the variable :c:data:`command` should "
"properly be declared as ``const char *command``)."
msgstr ""
#: ../../extending/extending.rst:289
msgid ""
"The next statement is a call to the Unix function :c:func:`system`, passing "
"it the string we just got from :c:func:`PyArg_ParseTuple`::"
msgstr ""
#: ../../extending/extending.rst:294
msgid ""
"Our :func:`spam.system` function must return the value of :c:data:`sts` as a "
"Python object. This is done using the function :c:func:`PyLong_FromLong`. ::"
msgstr ""
#: ../../extending/extending.rst:299
msgid ""
"In this case, it will return an integer object. (Yes, even integers are "
"objects on the heap in Python!)"
msgstr ""
#: ../../extending/extending.rst:302
msgid ""
"If you have a C function that returns no useful argument (a function "
"returning :c:type:`void`), the corresponding Python function must return "
"``None``. You need this idiom to do so (which is implemented by "
"the :c:macro:`Py_RETURN_NONE` macro)::"
msgstr ""
#: ../../extending/extending.rst:310
msgid ""
":c:data:`Py_None` is the C name for the special Python object ``None``. It "
"is a genuine Python object rather than a ``NULL`` pointer, which means "
"\"error\" in most contexts, as we have seen."
msgstr ""
#: ../../extending/extending.rst:318
msgid "The Module's Method Table and Initialization Function"
msgstr ""
#: ../../extending/extending.rst:320
msgid ""
"I promised to show how :c:func:`spam_system` is called from Python programs. "
"First, we need to list its name and address in a \"method table\"::"
msgstr ""
#: ../../extending/extending.rst:331
msgid ""
"Note the third entry (``METH_VARARGS``). This is a flag telling the "
"interpreter the calling convention to be used for the C function. It should "
"normally always be ``METH_VARARGS`` or ``METH_VARARGS | METH_KEYWORDS``; a "
"value of ``0`` means that an obsolete variant of :c:func:`PyArg_ParseTuple` "
"is used."
msgstr ""
#: ../../extending/extending.rst:336
msgid ""
"When using only ``METH_VARARGS``, the function should expect the Python-"
"level parameters to be passed in as a tuple acceptable for parsing "
"via :c:func:`PyArg_ParseTuple`; more information on this function is "
"provided below."
msgstr ""
#: ../../extending/extending.rst:340
msgid ""
"The :const:`METH_KEYWORDS` bit may be set in the third field if keyword "
"arguments should be passed to the function. In this case, the C function "
"should accept a third ``PyObject *`` parameter which will be a dictionary of "
"keywords. Use :c:func:`PyArg_ParseTupleAndKeywords` to parse the arguments "
"to such a function."
msgstr ""
#: ../../extending/extending.rst:346
msgid ""
"The method table must be referenced in the module definition structure::"
msgstr ""
#: ../../extending/extending.rst:357
msgid ""
"This structure, in turn, must be passed to the interpreter in the module's "
"initialization function. The initialization function must be "
"named :c:func:`PyInit_name`, where *name* is the name of the module, and "
"should be the only non-\\ ``static`` item defined in the module file::"
msgstr ""
#: ../../extending/extending.rst:368
msgid ""
"Note that PyMODINIT_FUNC declares the function as ``PyObject *`` return "
"type, declares any special linkage declarations required by the platform, "
"and for C++ declares the function as ``extern \"C\"``."
msgstr ""
#: ../../extending/extending.rst:372
msgid ""
"When the Python program imports module :mod:`spam` for the first "
"time, :c:func:`PyInit_spam` is called. (See below for comments about "
"embedding Python.) It calls :c:func:`PyModule_Create`, which returns a "
"module object, and inserts built-in function objects into the newly created "
"module based upon the table (an array of :c:type:`PyMethodDef` structures) "
"found in the module definition. :c:func:`PyModule_Create` returns a pointer "
"to the module object that it creates. It may abort with a fatal error for "
"certain errors, or return ``NULL`` if the module could not be initialized "
"satisfactorily. The init function must return the module object to its "
"caller, so that it then gets inserted into ``sys.modules``."
msgstr ""
#: ../../extending/extending.rst:383
msgid ""
"When embedding Python, the :c:func:`PyInit_spam` function is not called "
"automatically unless there's an entry in the :c:data:`PyImport_Inittab` "
"table. To add the module to the initialization table, "
"use :c:func:`PyImport_AppendInittab`, optionally followed by an import of "
"the module::"
msgstr ""
#: ../../extending/extending.rst:427
msgid ""
"Removing entries from ``sys.modules`` or importing compiled modules into "
"multiple interpreters within a process (or following a :c:func:`fork` "
"without an intervening :c:func:`exec`) can create problems for some "
"extension modules. Extension module authors should exercise caution when "
"initializing internal data structures."
msgstr ""
#: ../../extending/extending.rst:433
msgid ""
"A more substantial example module is included in the Python source "
"distribution as :file:`Modules/xxmodule.c`. This file may be used as a "
"template or simply read as an example."
msgstr ""
#: ../../extending/extending.rst:439
msgid ""
"Unlike our ``spam`` example, ``xxmodule`` uses *multi-phase initialization* "
"(new in Python 3.5), where a PyModuleDef structure is returned from "
"``PyInit_spam``, and creation of the module is left to the import machinery. "
"For details on multi-phase initialization, see :PEP:`489`."
msgstr ""
#: ../../extending/extending.rst:448
msgid "Compilation and Linkage"
msgstr ""
#: ../../extending/extending.rst:450
msgid ""
"There are two more things to do before you can use your new extension: "
"compiling and linking it with the Python system. If you use dynamic "
"loading, the details may depend on the style of dynamic loading your system "
"uses; see the chapters about building extension modules "
"(chapter :ref:`building`) and additional information that pertains only to "
"building on Windows (chapter :ref:`building-on-windows`) for more "
"information about this."
msgstr ""
#: ../../extending/extending.rst:457
msgid ""
"If you can't use dynamic loading, or if you want to make your module a "
"permanent part of the Python interpreter, you will have to change the "
"configuration setup and rebuild the interpreter. Luckily, this is very "
"simple on Unix: just place your file (:file:`spammodule.c` for example) in "
"the :file:`Modules/` directory of an unpacked source distribution, add a "
"line to the file :file:`Modules/Setup.local` describing your file:"
msgstr ""
#: ../../extending/extending.rst:468
msgid ""
"and rebuild the interpreter by running :program:`make` in the toplevel "
"directory. You can also run :program:`make` in the :file:`Modules/` "
"subdirectory, but then you must first rebuild :file:`Makefile` there by "
"running ':program:`make` Makefile'. (This is necessary each time you change "
"the :file:`Setup` file.)"
msgstr ""
#: ../../extending/extending.rst:474
msgid ""
"If your module requires additional libraries to link with, these can be "
"listed on the line in the configuration file as well, for instance:"
msgstr ""
#: ../../extending/extending.rst:485
msgid "Calling Python Functions from C"
msgstr ""
#: ../../extending/extending.rst:487
msgid ""
"So far we have concentrated on making C functions callable from Python. The "
"reverse is also useful: calling Python functions from C. This is especially "
"the case for libraries that support so-called \"callback\" functions. If a "
"C interface makes use of callbacks, the equivalent Python often needs to "
"provide a callback mechanism to the Python programmer; the implementation "
"will require calling the Python callback functions from a C callback. Other "
"uses are also imaginable."
msgstr ""
#: ../../extending/extending.rst:495
msgid ""
"Fortunately, the Python interpreter is easily called recursively, and there "
"is a standard interface to call a Python function. (I won't dwell on how to "
"call the Python parser with a particular string as input --- if you're "
"interested, have a look at the implementation of the :option:`-c` command "
"line option in :file:`Modules/main.c` from the Python source code.)"
msgstr ""
#: ../../extending/extending.rst:501
msgid ""
"Calling a Python function is easy. First, the Python program must somehow "
"pass you the Python function object. You should provide a function (or some "
"other interface) to do this. When this function is called, save a pointer "
"to the Python function object (be careful to :c:func:`Py_INCREF` it!) in a "
"global variable --- or wherever you see fit. For example, the following "
"function might be part of a module definition::"
msgstr ""
#: ../../extending/extending.rst:531
msgid ""
"This function must be registered with the interpreter using "
"the :const:`METH_VARARGS` flag; this is described in "
"section :ref:`methodtable`. The :c:func:`PyArg_ParseTuple` function and its "
"arguments are documented in section :ref:`parsetuple`."
msgstr ""
#: ../../extending/extending.rst:536
msgid ""
"The macros :c:func:`Py_XINCREF` and :c:func:`Py_XDECREF` increment/decrement "
"the reference count of an object and are safe in the presence of ``NULL`` "
"pointers (but note that *temp* will not be ``NULL`` in this context). More "
"info on them in section :ref:`refcounts`."
msgstr ""
#: ../../extending/extending.rst:543
msgid ""
"Later, when it is time to call the function, you call the C "
"function :c:func:`PyObject_CallObject`. This function has two arguments, "
"both pointers to arbitrary Python objects: the Python function, and the "
"argument list. The argument list must always be a tuple object, whose "
"length is the number of arguments. To call the Python function with no "
"arguments, pass in ``NULL``, or an empty tuple; to call it with one "
"argument, pass a singleton tuple. :c:func:`Py_BuildValue` returns a tuple "
"when its format string consists of zero or more format codes between "
"parentheses. For example::"
msgstr ""
#: ../../extending/extending.rst:563
msgid ""
":c:func:`PyObject_CallObject` returns a Python object pointer: this is the "
"return value of the Python function. :c:func:`PyObject_CallObject` is "
"\"reference-count-neutral\" with respect to its arguments. In the example a "
"new tuple was created to serve as the argument list, which "
"is :c:func:`Py_DECREF`\\ -ed immediately after "
"the :c:func:`PyObject_CallObject` call."
msgstr ""
#: ../../extending/extending.rst:570
msgid ""
"The return value of :c:func:`PyObject_CallObject` is \"new\": either it is a "
"brand new object, or it is an existing object whose reference count has been "
"incremented. So, unless you want to save it in a global variable, you "
"should somehow :c:func:`Py_DECREF` the result, even (especially!) if you are "
"not interested in its value."
msgstr ""
#: ../../extending/extending.rst:576
msgid ""
"Before you do this, however, it is important to check that the return value "
"isn't ``NULL``. If it is, the Python function terminated by raising an "
"exception. If the C code that called :c:func:`PyObject_CallObject` is called "
"from Python, it should now return an error indication to its Python caller, "
"so the interpreter can print a stack trace, or the calling Python code can "
"handle the exception. If this is not possible or desirable, the exception "
"should be cleared by calling :c:func:`PyErr_Clear`. For example::"
msgstr ""
#: ../../extending/extending.rst:589
msgid ""
"Depending on the desired interface to the Python callback function, you may "
"also have to provide an argument list to :c:func:`PyObject_CallObject`. In "
"some cases the argument list is also provided by the Python program, through "
"the same interface that specified the callback function. It can then be "
"saved and used in the same manner as the function object. In other cases, "
"you may have to construct a new tuple to pass as the argument list. The "
"simplest way to do this is to call :c:func:`Py_BuildValue`. For example, if "
"you want to pass an integral event code, you might use the following code::"
msgstr ""
#: ../../extending/extending.rst:608
msgid ""
"Note the placement of ``Py_DECREF(arglist)`` immediately after the call, "
"before the error check! Also note that strictly speaking this code is not "
"complete: :c:func:`Py_BuildValue` may run out of memory, and this should be "
"checked."
msgstr ""
#: ../../extending/extending.rst:612
msgid ""
"You may also call a function with keyword arguments by "
"using :c:func:`PyObject_Call`, which supports arguments and keyword "
"arguments. As in the above example, we use :c:func:`Py_BuildValue` to "
"construct the dictionary. ::"
msgstr ""
#: ../../extending/extending.rst:630
msgid "Extracting Parameters in Extension Functions"
msgstr ""
#: ../../extending/extending.rst:634
msgid "The :c:func:`PyArg_ParseTuple` function is declared as follows::"
msgstr ""
#: ../../extending/extending.rst:638
msgid ""
"The *arg* argument must be a tuple object containing an argument list passed "
"from Python to a C function. The *format* argument must be a format string, "
"whose syntax is explained in :ref:`arg-parsing` in the Python/C API "
"Reference Manual. The remaining arguments must be addresses of variables "
"whose type is determined by the format string."
msgstr ""
#: ../../extending/extending.rst:644
msgid ""
"Note that while :c:func:`PyArg_ParseTuple` checks that the Python arguments "
"have the required types, it cannot check the validity of the addresses of C "
"variables passed to the call: if you make mistakes there, your code will "
"probably crash or at least overwrite random bits in memory. So be careful!"
msgstr ""
#: ../../extending/extending.rst:649
msgid ""
"Note that any Python object references which are provided to the caller are "
"*borrowed* references; do not decrement their reference count!"
msgstr ""
"Note que quaisquer referências a objeto Python que são fornecidas ao "
"chamador são referências *emprestadas*; não decremente a contagem de "
"referências delas!"
#: ../../extending/extending.rst:652
msgid "Some example calls::"
msgstr ""
#: ../../extending/extending.rst:722
msgid "Keyword Parameters for Extension Functions"
msgstr ""
#: ../../extending/extending.rst:726
msgid ""
"The :c:func:`PyArg_ParseTupleAndKeywords` function is declared as follows::"
msgstr ""
#: ../../extending/extending.rst:731
msgid ""
"The *arg* and *format* parameters are identical to those of "
"the :c:func:`PyArg_ParseTuple` function. The *kwdict* parameter is the "
"dictionary of keywords received as the third parameter from the Python "
"runtime. The *kwlist* parameter is a ``NULL``-terminated list of strings "
"which identify the parameters; the names are matched with the type "
"information from *format* from left to right. On "
"success, :c:func:`PyArg_ParseTupleAndKeywords` returns true, otherwise it "
"returns false and raises an appropriate exception."
msgstr ""
#: ../../extending/extending.rst:741
msgid ""
"Nested tuples cannot be parsed when using keyword arguments! Keyword "
"parameters passed in which are not present in the *kwlist* will "
"cause :exc:`TypeError` to be raised."
msgstr ""
#: ../../extending/extending.rst:747
msgid ""
"Here is an example module which uses keywords, based on an example by Geoff "
"Philbrick (philbrick@hks.com)::"
msgstr ""
#: ../../extending/extending.rst:802
msgid "Building Arbitrary Values"
msgstr ""
#: ../../extending/extending.rst:804
msgid ""
"This function is the counterpart to :c:func:`PyArg_ParseTuple`. It is "
"declared as follows::"
msgstr ""
#: ../../extending/extending.rst:809
msgid ""
"It recognizes a set of format units similar to the ones recognized "
"by :c:func:`PyArg_ParseTuple`, but the arguments (which are input to the "
"function, not output) must not be pointers, just values. It returns a new "
"Python object, suitable for returning from a C function called from Python."
msgstr ""
#: ../../extending/extending.rst:814
msgid ""
"One difference with :c:func:`PyArg_ParseTuple`: while the latter requires "
"its first argument to be a tuple (since Python argument lists are always "
"represented as tuples internally), :c:func:`Py_BuildValue` does not always "
"build a tuple. It builds a tuple only if its format string contains two or "
"more format units. If the format string is empty, it returns ``None``; if it "
"contains exactly one format unit, it returns whatever object is described by "
"that format unit. To force it to return a tuple of size 0 or one, "
"parenthesize the format string."
msgstr ""
#: ../../extending/extending.rst:822
msgid ""
"Examples (to the left the call, to the right the resulting Python value):"
msgstr ""
#: ../../extending/extending.rst:848
msgid "Reference Counts"
msgstr "Contagens de referências"
#: ../../extending/extending.rst:850
msgid ""
"In languages like C or C++, the programmer is responsible for dynamic "
"allocation and deallocation of memory on the heap. In C, this is done using "
"the functions :c:func:`malloc` and :c:func:`free`. In C++, the operators "
"``new`` and ``delete`` are used with essentially the same meaning and we'll "
"restrict the following discussion to the C case."
msgstr ""
#: ../../extending/extending.rst:856
msgid ""
"Every block of memory allocated with :c:func:`malloc` should eventually be "
"returned to the pool of available memory by exactly one call "
"to :c:func:`free`. It is important to call :c:func:`free` at the right "
"time. If a block's address is forgotten but :c:func:`free` is not called "
"for it, the memory it occupies cannot be reused until the program "
"terminates. This is called a :dfn:`memory leak`. On the other hand, if a "
"program calls :c:func:`free` for a block and then continues to use the "
"block, it creates a conflict with re-use of the block through "
"another :c:func:`malloc` call. This is called :dfn:`using freed memory`. It "
"has the same bad consequences as referencing uninitialized data --- core "
"dumps, wrong results, mysterious crashes."
msgstr ""
#: ../../extending/extending.rst:867
msgid ""
"Common causes of memory leaks are unusual paths through the code. For "
"instance, a function may allocate a block of memory, do some calculation, "
"and then free the block again. Now a change in the requirements for the "
"function may add a test to the calculation that detects an error condition "
"and can return prematurely from the function. It's easy to forget to free "
"the allocated memory block when taking this premature exit, especially when "
"it is added later to the code. Such leaks, once introduced, often go "
"undetected for a long time: the error exit is taken only in a small fraction "
"of all calls, and most modern machines have plenty of virtual memory, so the "
"leak only becomes apparent in a long-running process that uses the leaking "
"function frequently. Therefore, it's important to prevent leaks from "
"happening by having a coding convention or strategy that minimizes this kind "
"of errors."
msgstr ""
#: ../../extending/extending.rst:880
msgid ""
"Since Python makes heavy use of :c:func:`malloc` and :c:func:`free`, it "
"needs a strategy to avoid memory leaks as well as the use of freed memory. "
"The chosen method is called :dfn:`reference counting`. The principle is "
"simple: every object contains a counter, which is incremented when a "
"reference to the object is stored somewhere, and which is decremented when a "
"reference to it is deleted. When the counter reaches zero, the last "
"reference to the object has been deleted and the object is freed."
msgstr ""
#: ../../extending/extending.rst:888
msgid ""
"An alternative strategy is called :dfn:`automatic garbage collection`. "
"(Sometimes, reference counting is also referred to as a garbage collection "
"strategy, hence my use of \"automatic\" to distinguish the two.) The big "
"advantage of automatic garbage collection is that the user doesn't need to "
"call :c:func:`free` explicitly. (Another claimed advantage is an "
"improvement in speed or memory usage --- this is no hard fact however.) The "
"disadvantage is that for C, there is no truly portable automatic garbage "
"collector, while reference counting can be implemented portably (as long as "
"the functions :c:func:`malloc` and :c:func:`free` are available --- which "
"the C Standard guarantees). Maybe some day a sufficiently portable automatic "
"garbage collector will be available for C. Until then, we'll have to live "
"with reference counts."
msgstr ""
#: ../../extending/extending.rst:900
msgid ""
"While Python uses the traditional reference counting implementation, it also "
"offers a cycle detector that works to detect reference cycles. This allows "
"applications to not worry about creating direct or indirect circular "
"references; these are the weakness of garbage collection implemented using "
"only reference counting. Reference cycles consist of objects which contain "
"(possibly indirect) references to themselves, so that each object in the "
"cycle has a reference count which is non-zero. Typical reference counting "
"implementations are not able to reclaim the memory belonging to any objects "
"in a reference cycle, or referenced from the objects in the cycle, even "
"though there are no further references to the cycle itself."
msgstr ""
#: ../../extending/extending.rst:911
msgid ""
"The cycle detector is able to detect garbage cycles and can reclaim them. "
"The :mod:`gc` module exposes a way to run the detector "
"(the :func:`~gc.collect` function), as well as configuration interfaces and "
"the ability to disable the detector at runtime. The cycle detector is "
"considered an optional component; though it is included by default, it can "
"be disabled at build time using the :option:`!--without-cycle-gc` option to "
"the :program:`configure` script on Unix platforms (including Mac OS X). If "
"the cycle detector is disabled in this way, the :mod:`gc` module will not be "
"available."
msgstr ""
#: ../../extending/extending.rst:925
msgid "Reference Counting in Python"
msgstr ""
#: ../../extending/extending.rst:927
msgid ""
"There are two macros, ``Py_INCREF(x)`` and ``Py_DECREF(x)``, which handle "
"the incrementing and decrementing of the reference "
"count. :c:func:`Py_DECREF` also frees the object when the count reaches "
"zero. For flexibility, it doesn't call :c:func:`free` directly --- rather, "
"it makes a call through a function pointer in the object's :dfn:`type "
"object`. For this purpose (and others), every object also contains a "
"pointer to its type object."
msgstr ""
#: ../../extending/extending.rst:934
msgid ""
"The big question now remains: when to use ``Py_INCREF(x)`` and "
"``Py_DECREF(x)``? Let's first introduce some terms. Nobody \"owns\" an "
"object; however, you can :dfn:`own a reference` to an object. An object's "
"reference count is now defined as the number of owned references to it. The "
"owner of a reference is responsible for calling :c:func:`Py_DECREF` when the "
"reference is no longer needed. Ownership of a reference can be "
"transferred. There are three ways to dispose of an owned reference: pass it "
"on, store it, or call :c:func:`Py_DECREF`. Forgetting to dispose of an owned "
"reference creates a memory leak."
msgstr ""
#: ../../extending/extending.rst:943
msgid ""
"It is also possible to :dfn:`borrow` [#]_ a reference to an object. The "
"borrower of a reference should not call :c:func:`Py_DECREF`. The borrower "
"must not hold on to the object longer than the owner from which it was "
"borrowed. Using a borrowed reference after the owner has disposed of it "
"risks using freed memory and should be avoided completely [#]_."
msgstr ""
#: ../../extending/extending.rst:949
msgid ""
"The advantage of borrowing over owning a reference is that you don't need to "
"take care of disposing of the reference on all possible paths through the "
"code --- in other words, with a borrowed reference you don't run the risk of "
"leaking when a premature exit is taken. The disadvantage of borrowing over "
"owning is that there are some subtle situations where in seemingly correct "
"code a borrowed reference can be used after the owner from which it was "
"borrowed has in fact disposed of it."
msgstr ""
#: ../../extending/extending.rst:957
msgid ""
"A borrowed reference can be changed into an owned reference by "
"calling :c:func:`Py_INCREF`. This does not affect the status of the owner "
"from which the reference was borrowed --- it creates a new owned reference, "
"and gives full owner responsibilities (the new owner must dispose of the "
"reference properly, as well as the previous owner)."
msgstr ""
#: ../../extending/extending.rst:967
msgid "Ownership Rules"
msgstr ""
#: ../../extending/extending.rst:969
msgid ""
"Whenever an object reference is passed into or out of a function, it is part "
"of the function's interface specification whether ownership is transferred "
"with the reference or not."
msgstr ""
#: ../../extending/extending.rst:973
msgid ""
"Most functions that return a reference to an object pass on ownership with "
"the reference. In particular, all functions whose function it is to create "
"a new object, such as :c:func:`PyLong_FromLong` and :c:func:`Py_BuildValue`, "
"pass ownership to the receiver. Even if the object is not actually new, you "
"still receive ownership of a new reference to that object. For "
"instance, :c:func:`PyLong_FromLong` maintains a cache of popular values and "
"can return a reference to a cached item."
msgstr ""
#: ../../extending/extending.rst:981
msgid ""
"Many functions that extract objects from other objects also transfer "
"ownership with the reference, for "
"instance :c:func:`PyObject_GetAttrString`. The picture is less clear, here, "
"however, since a few common routines are "
"exceptions: :c:func:`PyTuple_GetItem`, :c:func:`PyList_GetItem`, :c:func:`PyDict_GetItem`, "
"and :c:func:`PyDict_GetItemString` all return references that you borrow "
"from the tuple, list or dictionary."
msgstr ""
#: ../../extending/extending.rst:988
msgid ""
"The function :c:func:`PyImport_AddModule` also returns a borrowed reference, "
"even though it may actually create the object it returns: this is possible "
"because an owned reference to the object is stored in ``sys.modules``."
msgstr ""
#: ../../extending/extending.rst:992
msgid ""
"When you pass an object reference into another function, in general, the "
"function borrows the reference from you --- if it needs to store it, it will "
"use :c:func:`Py_INCREF` to become an independent owner. There are exactly "