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Jeroen Ruigrok van der Werven
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@ -10,46 +10,48 @@ methods. Additional information and examples are available in
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:ref:`extending-index`.
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The first three of these functions described, :cfunc:`PyArg_ParseTuple`,
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:cfunc:`PyArg_ParseTupleAndKeywords`, and :cfunc:`PyArg_Parse`, all use *format
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strings* which are used to tell the function about the expected arguments. The
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format strings use the same syntax for each of these functions.
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:cfunc:`PyArg_ParseTupleAndKeywords`, and :cfunc:`PyArg_Parse`, all use
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*format strings* which are used to tell the function about the expected
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arguments. The format strings use the same syntax for each of these
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functions.
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A format string consists of zero or more "format units." A format unit
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describes one Python object; it is usually a single character or a parenthesized
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sequence of format units. With a few exceptions, a format unit that is not a
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parenthesized sequence normally corresponds to a single address argument to
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these functions. In the following description, the quoted form is the format
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unit; the entry in (round) parentheses is the Python object type that matches
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the format unit; and the entry in [square] brackets is the type of the C
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variable(s) whose address should be passed.
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describes one Python object; it is usually a single character or a
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parenthesized sequence of format units. With a few exceptions, a format unit
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that is not a parenthesized sequence normally corresponds to a single address
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argument to these functions. In the following description, the quoted form is
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the format unit; the entry in (round) parentheses is the Python object type
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that matches the format unit; and the entry in [square] brackets is the type
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of the C variable(s) whose address should be passed.
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``s`` (string or Unicode object) [const char \*]
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Convert a Python string or Unicode object to a C pointer to a character string.
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You must not provide storage for the string itself; a pointer to an existing
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string is stored into the character pointer variable whose address you pass.
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The C string is NUL-terminated. The Python string must not contain embedded NUL
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bytes; if it does, a :exc:`TypeError` exception is raised. Unicode objects are
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converted to C strings using the default encoding. If this conversion fails, a
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:exc:`UnicodeError` is raised.
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Convert a Python string or Unicode object to a C pointer to a character
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string. You must not provide storage for the string itself; a pointer to
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an existing string is stored into the character pointer variable whose
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address you pass. The C string is NUL-terminated. The Python string must
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not contain embedded NUL bytes; if it does, a :exc:`TypeError` exception is
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raised. Unicode objects are converted to C strings using the default
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encoding. If this conversion fails, a :exc:`UnicodeError` is raised.
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``s#`` (string, Unicode or any read buffer compatible object) [const char \*, int (or :ctype:`Py_ssize_t`, see below)]
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This variant on ``s`` stores into two C variables, the first one a pointer to a
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character string, the second one its length. In this case the Python string may
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contain embedded null bytes. Unicode objects pass back a pointer to the default
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encoded string version of the object if such a conversion is possible. All
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other read-buffer compatible objects pass back a reference to the raw internal
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data representation.
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This variant on ``s`` stores into two C variables, the first one a pointer
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to a character string, the second one its length. In this case the Python
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string may contain embedded null bytes. Unicode objects pass back a
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pointer to the default encoded string version of the object if such a
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conversion is possible. All other read-buffer compatible objects pass back
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a reference to the raw internal data representation.
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Starting with Python 2.5 the type of the length argument can be
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controlled by defining the macro :cmacro:`PY_SSIZE_T_CLEAN` before
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including :file:`Python.h`. If the macro is defined, length is a
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:ctype:`Py_ssize_t` rather than an int.
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Starting with Python 2.5 the type of the length argument can be controlled
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by defining the macro :cmacro:`PY_SSIZE_T_CLEAN` before including
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:file:`Python.h`. If the macro is defined, length is a :ctype:`Py_ssize_t`
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rather than an int.
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``s*`` (string, Unicode, or any buffer compatible object) [Py_buffer \*]
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Similar to ``s#``, this code fills a Py_buffer structure provided by the caller.
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The buffer gets locked, so that the caller can subsequently use the buffer even
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inside a ``Py_BEGIN_ALLOW_THREADS`` block; the caller is responsible for calling
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``PyBuffer_Release`` with the structure after it has processed the data.
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Similar to ``s#``, this code fills a Py_buffer structure provided by the
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caller. The buffer gets locked, so that the caller can subsequently use
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the buffer even inside a ``Py_BEGIN_ALLOW_THREADS`` block; the caller is
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responsible for calling ``PyBuffer_Release`` with the structure after it
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has processed the data.
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.. versionadded:: 2.6
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@ -66,83 +68,86 @@ variable(s) whose address should be passed.
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.. versionadded:: 2.6
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``u`` (Unicode object) [Py_UNICODE \*]
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Convert a Python Unicode object to a C pointer to a NUL-terminated buffer of
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16-bit Unicode (UTF-16) data. As with ``s``, there is no need to provide
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storage for the Unicode data buffer; a pointer to the existing Unicode data is
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stored into the :ctype:`Py_UNICODE` pointer variable whose address you pass.
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Convert a Python Unicode object to a C pointer to a NUL-terminated buffer
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of 16-bit Unicode (UTF-16) data. As with ``s``, there is no need to
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provide storage for the Unicode data buffer; a pointer to the existing
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Unicode data is stored into the :ctype:`Py_UNICODE` pointer variable whose
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address you pass.
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``u#`` (Unicode object) [Py_UNICODE \*, int]
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This variant on ``u`` stores into two C variables, the first one a pointer to a
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Unicode data buffer, the second one its length. Non-Unicode objects are handled
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by interpreting their read-buffer pointer as pointer to a :ctype:`Py_UNICODE`
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array.
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This variant on ``u`` stores into two C variables, the first one a pointer
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to a Unicode data buffer, the second one its length. Non-Unicode objects
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are handled by interpreting their read-buffer pointer as pointer to a
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:ctype:`Py_UNICODE` array.
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``es`` (string, Unicode object or character buffer compatible object) [const char \*encoding, char \*\*buffer]
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This variant on ``s`` is used for encoding Unicode and objects convertible to
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Unicode into a character buffer. It only works for encoded data without embedded
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NUL bytes.
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This variant on ``s`` is used for encoding Unicode and objects convertible
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to Unicode into a character buffer. It only works for encoded data without
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embedded NUL bytes.
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This format requires two arguments. The first is only used as input, and
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must be a :ctype:`const char\*` which points to the name of an encoding as a
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NUL-terminated string, or *NULL*, in which case the default encoding is used.
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An exception is raised if the named encoding is not known to Python. The
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second argument must be a :ctype:`char\*\*`; the value of the pointer it
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references will be set to a buffer with the contents of the argument text.
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The text will be encoded in the encoding specified by the first argument.
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must be a :ctype:`const char\*` which points to the name of an encoding as
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a NUL-terminated string, or *NULL*, in which case the default encoding is
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used. An exception is raised if the named encoding is not known to Python.
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The second argument must be a :ctype:`char\*\*`; the value of the pointer
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it references will be set to a buffer with the contents of the argument
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text. The text will be encoded in the encoding specified by the first
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argument.
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:cfunc:`PyArg_ParseTuple` will allocate a buffer of the needed size, copy the
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encoded data into this buffer and adjust *\*buffer* to reference the newly
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allocated storage. The caller is responsible for calling :cfunc:`PyMem_Free` to
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free the allocated buffer after use.
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:cfunc:`PyArg_ParseTuple` will allocate a buffer of the needed size, copy
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the encoded data into this buffer and adjust *\*buffer* to reference the
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newly allocated storage. The caller is responsible for calling
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:cfunc:`PyMem_Free` to free the allocated buffer after use.
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``et`` (string, Unicode object or character buffer compatible object) [const char \*encoding, char \*\*buffer]
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Same as ``es`` except that 8-bit string objects are passed through without
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recoding them. Instead, the implementation assumes that the string object uses
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the encoding passed in as parameter.
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recoding them. Instead, the implementation assumes that the string object
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uses the encoding passed in as parameter.
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``es#`` (string, Unicode object or character buffer compatible object) [const char \*encoding, char \*\*buffer, int \*buffer_length]
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This variant on ``s#`` is used for encoding Unicode and objects convertible to
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Unicode into a character buffer. Unlike the ``es`` format, this variant allows
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input data which contains NUL characters.
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This variant on ``s#`` is used for encoding Unicode and objects convertible
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to Unicode into a character buffer. Unlike the ``es`` format, this variant
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allows input data which contains NUL characters.
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It requires three arguments. The first is only used as input, and must be a
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:ctype:`const char\*` which points to the name of an encoding as a
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NUL-terminated string, or *NULL*, in which case the default encoding is used.
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An exception is raised if the named encoding is not known to Python. The
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second argument must be a :ctype:`char\*\*`; the value of the pointer it
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references will be set to a buffer with the contents of the argument text.
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The text will be encoded in the encoding specified by the first argument.
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The third argument must be a pointer to an integer; the referenced integer
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will be set to the number of bytes in the output buffer.
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It requires three arguments. The first is only used as input, and must be
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a :ctype:`const char\*` which points to the name of an encoding as a
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NUL-terminated string, or *NULL*, in which case the default encoding is
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used. An exception is raised if the named encoding is not known to Python.
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The second argument must be a :ctype:`char\*\*`; the value of the pointer
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it references will be set to a buffer with the contents of the argument
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text. The text will be encoded in the encoding specified by the first
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argument. The third argument must be a pointer to an integer; the
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referenced integer will be set to the number of bytes in the output buffer.
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There are two modes of operation:
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If *\*buffer* points a *NULL* pointer, the function will allocate a buffer of
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the needed size, copy the encoded data into this buffer and set *\*buffer* to
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reference the newly allocated storage. The caller is responsible for calling
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:cfunc:`PyMem_Free` to free the allocated buffer after usage.
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If *\*buffer* points a *NULL* pointer, the function will allocate a buffer
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of the needed size, copy the encoded data into this buffer and set
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*\*buffer* to reference the newly allocated storage. The caller is
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responsible for calling :cfunc:`PyMem_Free` to free the allocated buffer
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after usage.
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If *\*buffer* points to a non-*NULL* pointer (an already allocated buffer),
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:cfunc:`PyArg_ParseTuple` will use this location as the buffer and interpret the
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initial value of *\*buffer_length* as the buffer size. It will then copy the
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encoded data into the buffer and NUL-terminate it. If the buffer is not large
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enough, a :exc:`ValueError` will be set.
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:cfunc:`PyArg_ParseTuple` will use this location as the buffer and
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interpret the initial value of *\*buffer_length* as the buffer size. It
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will then copy the encoded data into the buffer and NUL-terminate it. If
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the buffer is not large enough, a :exc:`ValueError` will be set.
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In both cases, *\*buffer_length* is set to the length of the encoded data
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without the trailing NUL byte.
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``et#`` (string, Unicode object or character buffer compatible object) [const char \*encoding, char \*\*buffer]
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Same as ``es#`` except that string objects are passed through without recoding
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them. Instead, the implementation assumes that the string object uses the
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encoding passed in as parameter.
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Same as ``es#`` except that string objects are passed through without
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recoding them. Instead, the implementation assumes that the string object
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uses the encoding passed in as parameter.
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``b`` (integer) [unsigned char]
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Convert a nonnegative Python integer to an unsigned tiny int, stored in a C
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:ctype:`unsigned char`.
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``B`` (integer) [unsigned char]
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Convert a Python integer to a tiny int without overflow checking, stored in a C
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:ctype:`unsigned char`.
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Convert a Python integer to a tiny int without overflow checking, stored in
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a C :ctype:`unsigned char`.
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.. versionadded:: 2.3
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@ -150,8 +155,8 @@ variable(s) whose address should be passed.
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Convert a Python integer to a C :ctype:`short int`.
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``H`` (integer) [unsigned short int]
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Convert a Python integer to a C :ctype:`unsigned short int`, without overflow
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checking.
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Convert a Python integer to a C :ctype:`unsigned short int`, without
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overflow checking.
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.. versionadded:: 2.3
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@ -168,20 +173,21 @@ variable(s) whose address should be passed.
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Convert a Python integer to a C :ctype:`long int`.
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``k`` (integer) [unsigned long]
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Convert a Python integer or long integer to a C :ctype:`unsigned long` without
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overflow checking.
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Convert a Python integer or long integer to a C :ctype:`unsigned long`
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without overflow checking.
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.. versionadded:: 2.3
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``L`` (integer) [PY_LONG_LONG]
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Convert a Python integer to a C :ctype:`long long`. This format is only
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available on platforms that support :ctype:`long long` (or :ctype:`_int64` on
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Windows).
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available on platforms that support :ctype:`long long` (or :ctype:`_int64`
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on Windows).
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``K`` (integer) [unsigned PY_LONG_LONG]
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Convert a Python integer or long integer to a C :ctype:`unsigned long long`
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without overflow checking. This format is only available on platforms that
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support :ctype:`unsigned long long` (or :ctype:`unsigned _int64` on Windows).
|
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support :ctype:`unsigned long long` (or :ctype:`unsigned _int64` on
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Windows).
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.. versionadded:: 2.3
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@ -204,60 +210,61 @@ variable(s) whose address should be passed.
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Convert a Python complex number to a C :ctype:`Py_complex` structure.
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``O`` (object) [PyObject \*]
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Store a Python object (without any conversion) in a C object pointer. The C
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program thus receives the actual object that was passed. The object's reference
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count is not increased. The pointer stored is not *NULL*.
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Store a Python object (without any conversion) in a C object pointer. The
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C program thus receives the actual object that was passed. The object's
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reference count is not increased. The pointer stored is not *NULL*.
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``O!`` (object) [*typeobject*, PyObject \*]
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Store a Python object in a C object pointer. This is similar to ``O``, but
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takes two C arguments: the first is the address of a Python type object, the
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second is the address of the C variable (of type :ctype:`PyObject\*`) into which
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the object pointer is stored. If the Python object does not have the required
|
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type, :exc:`TypeError` is raised.
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takes two C arguments: the first is the address of a Python type object,
|
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the second is the address of the C variable (of type :ctype:`PyObject\*`)
|
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into which the object pointer is stored. If the Python object does not
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have the required type, :exc:`TypeError` is raised.
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``O&`` (object) [*converter*, *anything*]
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Convert a Python object to a C variable through a *converter* function. This
|
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takes two arguments: the first is a function, the second is the address of a C
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variable (of arbitrary type), converted to :ctype:`void \*`. The *converter*
|
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function in turn is called as follows::
|
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Convert a Python object to a C variable through a *converter* function.
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This takes two arguments: the first is a function, the second is the
|
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address of a C variable (of arbitrary type), converted to :ctype:`void \*`.
|
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The *converter* function in turn is called as follows::
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status = converter(object, address);
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where *object* is the Python object to be converted and *address* is the
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:ctype:`void\*` argument that was passed to the :cfunc:`PyArg_Parse\*` function.
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The returned *status* should be ``1`` for a successful conversion and ``0`` if
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the conversion has failed. When the conversion fails, the *converter* function
|
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should raise an exception and leave the content of *address* unmodified.
|
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:ctype:`void\*` argument that was passed to the :cfunc:`PyArg_Parse\*`
|
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function. The returned *status* should be ``1`` for a successful
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conversion and ``0`` if the conversion has failed. When the conversion
|
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fails, the *converter* function should raise an exception and leave the
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content of *address* unmodified.
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``S`` (string) [PyStringObject \*]
|
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Like ``O`` but requires that the Python object is a string object. Raises
|
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:exc:`TypeError` if the object is not a string object. The C variable may also
|
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be declared as :ctype:`PyObject\*`.
|
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:exc:`TypeError` if the object is not a string object. The C variable may
|
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also be declared as :ctype:`PyObject\*`.
|
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|
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``U`` (Unicode string) [PyUnicodeObject \*]
|
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Like ``O`` but requires that the Python object is a Unicode object. Raises
|
||||
:exc:`TypeError` if the object is not a Unicode object. The C variable may also
|
||||
be declared as :ctype:`PyObject\*`.
|
||||
:exc:`TypeError` if the object is not a Unicode object. The C variable may
|
||||
also be declared as :ctype:`PyObject\*`.
|
||||
|
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``t#`` (read-only character buffer) [char \*, int]
|
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Like ``s#``, but accepts any object which implements the read-only buffer
|
||||
interface. The :ctype:`char\*` variable is set to point to the first byte of
|
||||
the buffer, and the :ctype:`int` is set to the length of the buffer. Only
|
||||
single-segment buffer objects are accepted; :exc:`TypeError` is raised for all
|
||||
others.
|
||||
interface. The :ctype:`char\*` variable is set to point to the first byte
|
||||
of the buffer, and the :ctype:`int` is set to the length of the buffer.
|
||||
Only single-segment buffer objects are accepted; :exc:`TypeError` is raised
|
||||
for all others.
|
||||
|
||||
``w`` (read-write character buffer) [char \*]
|
||||
Similar to ``s``, but accepts any object which implements the read-write buffer
|
||||
interface. The caller must determine the length of the buffer by other means,
|
||||
or use ``w#`` instead. Only single-segment buffer objects are accepted;
|
||||
:exc:`TypeError` is raised for all others.
|
||||
Similar to ``s``, but accepts any object which implements the read-write
|
||||
buffer interface. The caller must determine the length of the buffer by
|
||||
other means, or use ``w#`` instead. Only single-segment buffer objects are
|
||||
accepted; :exc:`TypeError` is raised for all others.
|
||||
|
||||
``w#`` (read-write character buffer) [char \*, Py_ssize_t]
|
||||
Like ``s#``, but accepts any object which implements the read-write buffer
|
||||
interface. The :ctype:`char \*` variable is set to point to the first byte of
|
||||
the buffer, and the :ctype:`int` is set to the length of the buffer. Only
|
||||
single-segment buffer objects are accepted; :exc:`TypeError` is raised for all
|
||||
others.
|
||||
interface. The :ctype:`char \*` variable is set to point to the first byte
|
||||
of the buffer, and the :ctype:`int` is set to the length of the buffer.
|
||||
Only single-segment buffer objects are accepted; :exc:`TypeError` is raised
|
||||
for all others.
|
||||
|
||||
``w*`` (read-write byte-oriented buffer) [Py_buffer \*]
|
||||
This is to ``w`` what ``s*`` is to ``s``.
|
||||
|
|
@ -265,72 +272,72 @@ variable(s) whose address should be passed.
|
|||
.. versionadded:: 2.6
|
||||
|
||||
``(items)`` (tuple) [*matching-items*]
|
||||
The object must be a Python sequence whose length is the number of format units
|
||||
in *items*. The C arguments must correspond to the individual format units in
|
||||
*items*. Format units for sequences may be nested.
|
||||
The object must be a Python sequence whose length is the number of format
|
||||
units in *items*. The C arguments must correspond to the individual format
|
||||
units in *items*. Format units for sequences may be nested.
|
||||
|
||||
.. note::
|
||||
|
||||
Prior to Python version 1.5.2, this format specifier only accepted a tuple
|
||||
containing the individual parameters, not an arbitrary sequence. Code which
|
||||
previously caused :exc:`TypeError` to be raised here may now proceed without an
|
||||
exception. This is not expected to be a problem for existing code.
|
||||
Prior to Python version 1.5.2, this format specifier only accepted a
|
||||
tuple containing the individual parameters, not an arbitrary sequence.
|
||||
Code which previously caused :exc:`TypeError` to be raised here may now
|
||||
proceed without an exception. This is not expected to be a problem for
|
||||
existing code.
|
||||
|
||||
It is possible to pass Python long integers where integers are requested;
|
||||
however no proper range checking is done --- the most significant bits are
|
||||
silently truncated when the receiving field is too small to receive the value
|
||||
(actually, the semantics are inherited from downcasts in C --- your mileage may
|
||||
vary).
|
||||
(actually, the semantics are inherited from downcasts in C --- your mileage
|
||||
may vary).
|
||||
|
||||
A few other characters have a meaning in a format string. These may not occur
|
||||
inside nested parentheses. They are:
|
||||
|
||||
``|``
|
||||
Indicates that the remaining arguments in the Python argument list are optional.
|
||||
The C variables corresponding to optional arguments should be initialized to
|
||||
their default value --- when an optional argument is not specified,
|
||||
:cfunc:`PyArg_ParseTuple` does not touch the contents of the corresponding C
|
||||
variable(s).
|
||||
Indicates that the remaining arguments in the Python argument list are
|
||||
optional. The C variables corresponding to optional arguments should be
|
||||
initialized to their default value --- when an optional argument is not
|
||||
specified, :cfunc:`PyArg_ParseTuple` does not touch the contents of the
|
||||
corresponding C variable(s).
|
||||
|
||||
``:``
|
||||
The list of format units ends here; the string after the colon is used as the
|
||||
function name in error messages (the "associated value" of the exception that
|
||||
:cfunc:`PyArg_ParseTuple` raises).
|
||||
The list of format units ends here; the string after the colon is used as
|
||||
the function name in error messages (the "associated value" of the
|
||||
exception that :cfunc:`PyArg_ParseTuple` raises).
|
||||
|
||||
``;``
|
||||
The list of format units ends here; the string after the semicolon is used as
|
||||
the error message *instead* of the default error message. ``:`` and ``;``
|
||||
mutually exclude each other.
|
||||
The list of format units ends here; the string after the semicolon is used
|
||||
as the error message *instead* of the default error message. ``:`` and
|
||||
``;`` mutually exclude each other.
|
||||
|
||||
Note that any Python object references which are provided to the caller are
|
||||
*borrowed* references; do not decrement their reference count!
|
||||
|
||||
Additional arguments passed to these functions must be addresses of variables
|
||||
whose type is determined by the format string; these are used to store values
|
||||
from the input tuple. There are a few cases, as described in the list of format
|
||||
units above, where these parameters are used as input values; they should match
|
||||
what is specified for the corresponding format unit in that case.
|
||||
from the input tuple. There are a few cases, as described in the list of
|
||||
format units above, where these parameters are used as input values; they
|
||||
should match what is specified for the corresponding format unit in that case.
|
||||
|
||||
For the conversion to succeed, the *arg* object must match the format
|
||||
and the format must be exhausted. On success, the
|
||||
:cfunc:`PyArg_Parse\*` functions return true, otherwise they return
|
||||
false and raise an appropriate exception. When the
|
||||
:cfunc:`PyArg_Parse\*` functions fail due to conversion failure in one
|
||||
of the format units, the variables at the addresses corresponding to that
|
||||
For the conversion to succeed, the *arg* object must match the format and the
|
||||
format must be exhausted. On success, the :cfunc:`PyArg_Parse\*` functions
|
||||
return true, otherwise they return false and raise an appropriate exception.
|
||||
When the :cfunc:`PyArg_Parse\*` functions fail due to conversion failure in
|
||||
one of the format units, the variables at the addresses corresponding to that
|
||||
and the following format units are left untouched.
|
||||
|
||||
|
||||
.. cfunction:: int PyArg_ParseTuple(PyObject *args, const char *format, ...)
|
||||
|
||||
Parse the parameters of a function that takes only positional parameters into
|
||||
local variables. Returns true on success; on failure, it returns false and
|
||||
raises the appropriate exception.
|
||||
Parse the parameters of a function that takes only positional parameters
|
||||
into local variables. Returns true on success; on failure, it returns
|
||||
false and raises the appropriate exception.
|
||||
|
||||
|
||||
.. cfunction:: int PyArg_VaParse(PyObject *args, const char *format, va_list vargs)
|
||||
|
||||
Identical to :cfunc:`PyArg_ParseTuple`, except that it accepts a va_list rather
|
||||
than a variable number of arguments.
|
||||
Identical to :cfunc:`PyArg_ParseTuple`, except that it accepts a va_list
|
||||
rather than a variable number of arguments.
|
||||
|
||||
|
||||
.. cfunction:: int PyArg_ParseTupleAndKeywords(PyObject *args, PyObject *kw, const char *format, char *keywords[], ...)
|
||||
|
|
@ -348,32 +355,33 @@ and the following format units are left untouched.
|
|||
|
||||
.. cfunction:: int PyArg_Parse(PyObject *args, const char *format, ...)
|
||||
|
||||
Function used to deconstruct the argument lists of "old-style" functions ---
|
||||
these are functions which use the :const:`METH_OLDARGS` parameter parsing
|
||||
method. This is not recommended for use in parameter parsing in new code, and
|
||||
most code in the standard interpreter has been modified to no longer use this
|
||||
for that purpose. It does remain a convenient way to decompose other tuples,
|
||||
however, and may continue to be used for that purpose.
|
||||
Function used to deconstruct the argument lists of "old-style" functions
|
||||
--- these are functions which use the :const:`METH_OLDARGS` parameter
|
||||
parsing method. This is not recommended for use in parameter parsing in
|
||||
new code, and most code in the standard interpreter has been modified to no
|
||||
longer use this for that purpose. It does remain a convenient way to
|
||||
decompose other tuples, however, and may continue to be used for that
|
||||
purpose.
|
||||
|
||||
|
||||
.. cfunction:: int PyArg_UnpackTuple(PyObject *args, const char *name, Py_ssize_t min, Py_ssize_t max, ...)
|
||||
|
||||
A simpler form of parameter retrieval which does not use a format string to
|
||||
specify the types of the arguments. Functions which use this method to retrieve
|
||||
their parameters should be declared as :const:`METH_VARARGS` in function or
|
||||
method tables. The tuple containing the actual parameters should be passed as
|
||||
*args*; it must actually be a tuple. The length of the tuple must be at least
|
||||
*min* and no more than *max*; *min* and *max* may be equal. Additional
|
||||
arguments must be passed to the function, each of which should be a pointer to a
|
||||
:ctype:`PyObject\*` variable; these will be filled in with the values from
|
||||
*args*; they will contain borrowed references. The variables which correspond
|
||||
to optional parameters not given by *args* will not be filled in; these should
|
||||
be initialized by the caller. This function returns true on success and false if
|
||||
*args* is not a tuple or contains the wrong number of elements; an exception
|
||||
will be set if there was a failure.
|
||||
specify the types of the arguments. Functions which use this method to
|
||||
retrieve their parameters should be declared as :const:`METH_VARARGS` in
|
||||
function or method tables. The tuple containing the actual parameters
|
||||
should be passed as *args*; it must actually be a tuple. The length of the
|
||||
tuple must be at least *min* and no more than *max*; *min* and *max* may be
|
||||
equal. Additional arguments must be passed to the function, each of which
|
||||
should be a pointer to a :ctype:`PyObject\*` variable; these will be filled
|
||||
in with the values from *args*; they will contain borrowed references. The
|
||||
variables which correspond to optional parameters not given by *args* will
|
||||
not be filled in; these should be initialized by the caller. This function
|
||||
returns true on success and false if *args* is not a tuple or contains the
|
||||
wrong number of elements; an exception will be set if there was a failure.
|
||||
|
||||
This is an example of the use of this function, taken from the sources for the
|
||||
:mod:`_weakref` helper module for weak references::
|
||||
This is an example of the use of this function, taken from the sources for
|
||||
the :mod:`_weakref` helper module for weak references::
|
||||
|
||||
static PyObject *
|
||||
weakref_ref(PyObject *self, PyObject *args)
|
||||
|
|
@ -388,8 +396,8 @@ and the following format units are left untouched.
|
|||
return result;
|
||||
}
|
||||
|
||||
The call to :cfunc:`PyArg_UnpackTuple` in this example is entirely equivalent to
|
||||
this call to :cfunc:`PyArg_ParseTuple`::
|
||||
The call to :cfunc:`PyArg_UnpackTuple` in this example is entirely
|
||||
equivalent to this call to :cfunc:`PyArg_ParseTuple`::
|
||||
|
||||
PyArg_ParseTuple(args, "O|O:ref", &object, &callback)
|
||||
|
||||
|
|
@ -398,40 +406,42 @@ and the following format units are left untouched.
|
|||
|
||||
.. cfunction:: PyObject* Py_BuildValue(const char *format, ...)
|
||||
|
||||
Create a new value based on a format string similar to those accepted by the
|
||||
:cfunc:`PyArg_Parse\*` family of functions and a sequence of values. Returns
|
||||
the value or *NULL* in the case of an error; an exception will be raised if
|
||||
*NULL* is returned.
|
||||
Create a new value based on a format string similar to those accepted by
|
||||
the :cfunc:`PyArg_Parse\*` family of functions and a sequence of values.
|
||||
Returns the value or *NULL* in the case of an error; an exception will be
|
||||
raised if *NULL* is returned.
|
||||
|
||||
:cfunc:`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.
|
||||
:cfunc:`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.
|
||||
|
||||
When memory buffers are passed as parameters to supply data to build objects, as
|
||||
for the ``s`` and ``s#`` formats, the required data is copied. Buffers provided
|
||||
by the caller are never referenced by the objects created by
|
||||
:cfunc:`Py_BuildValue`. In other words, if your code invokes :cfunc:`malloc`
|
||||
and passes the allocated memory to :cfunc:`Py_BuildValue`, your code is
|
||||
responsible for calling :cfunc:`free` for that memory once
|
||||
When memory buffers are passed as parameters to supply data to build
|
||||
objects, as for the ``s`` and ``s#`` formats, the required data is copied.
|
||||
Buffers provided by the caller are never referenced by the objects created
|
||||
by :cfunc:`Py_BuildValue`. In other words, if your code invokes
|
||||
:cfunc:`malloc` and passes the allocated memory to :cfunc:`Py_BuildValue`,
|
||||
your code is responsible for calling :cfunc:`free` for that memory once
|
||||
:cfunc:`Py_BuildValue` returns.
|
||||
|
||||
In the following description, the quoted form is the format unit; the entry in
|
||||
(round) parentheses is the Python object type that the format unit will return;
|
||||
and the entry in [square] brackets is the type of the C value(s) to be passed.
|
||||
In the following description, the quoted form is the format unit; the entry
|
||||
in (round) parentheses is the Python object type that the format unit will
|
||||
return; and the entry in [square] brackets is the type of the C value(s) to
|
||||
be passed.
|
||||
|
||||
The characters space, tab, colon and comma are ignored in format strings (but
|
||||
not within format units such as ``s#``). This can be used to make long format
|
||||
strings a tad more readable.
|
||||
The characters space, tab, colon and comma are ignored in format strings
|
||||
(but not within format units such as ``s#``). This can be used to make
|
||||
long format strings a tad more readable.
|
||||
|
||||
``s`` (string) [char \*]
|
||||
Convert a null-terminated C string to a Python object. If the C string pointer
|
||||
is *NULL*, ``None`` is used.
|
||||
Convert a null-terminated C string to a Python object. If the C string
|
||||
pointer is *NULL*, ``None`` is used.
|
||||
|
||||
``s#`` (string) [char \*, int]
|
||||
Convert a C string and its length to a Python object. If the C string pointer
|
||||
is *NULL*, the length is ignored and ``None`` is returned.
|
||||
Convert a C string and its length to a Python object. If the C string
|
||||
pointer is *NULL*, the length is ignored and ``None`` is returned.
|
||||
|
||||
``z`` (string or ``None``) [char \*]
|
||||
Same as ``s``.
|
||||
|
|
@ -440,13 +450,14 @@ and the following format units are left untouched.
|
|||
Same as ``s#``.
|
||||
|
||||
``u`` (Unicode string) [Py_UNICODE \*]
|
||||
Convert a null-terminated buffer of Unicode (UCS-2 or UCS-4) data to a Python
|
||||
Unicode object. If the Unicode buffer pointer is *NULL*, ``None`` is returned.
|
||||
Convert a null-terminated buffer of Unicode (UCS-2 or UCS-4) data to a
|
||||
Python Unicode object. If the Unicode buffer pointer is *NULL*,
|
||||
``None`` is returned.
|
||||
|
||||
``u#`` (Unicode string) [Py_UNICODE \*, int]
|
||||
Convert a Unicode (UCS-2 or UCS-4) data buffer and its length to a Python
|
||||
Unicode object. If the Unicode buffer pointer is *NULL*, the length is ignored
|
||||
and ``None`` is returned.
|
||||
Convert a Unicode (UCS-2 or UCS-4) data buffer and its length to a
|
||||
Python Unicode object. If the Unicode buffer pointer is *NULL*, the
|
||||
length is ignored and ``None`` is returned.
|
||||
|
||||
``i`` (integer) [int]
|
||||
Convert a plain C :ctype:`int` to a Python integer object.
|
||||
|
|
@ -467,20 +478,20 @@ and the following format units are left untouched.
|
|||
Convert a C :ctype:`unsigned short int` to a Python integer object.
|
||||
|
||||
``I`` (integer/long) [unsigned int]
|
||||
Convert a C :ctype:`unsigned int` to a Python integer object or a Python long
|
||||
integer object, if it is larger than ``sys.maxint``.
|
||||
Convert a C :ctype:`unsigned int` to a Python integer object or a Python
|
||||
long integer object, if it is larger than ``sys.maxint``.
|
||||
|
||||
``k`` (integer/long) [unsigned long]
|
||||
Convert a C :ctype:`unsigned long` to a Python integer object or a Python long
|
||||
integer object, if it is larger than ``sys.maxint``.
|
||||
Convert a C :ctype:`unsigned long` to a Python integer object or a
|
||||
Python long integer object, if it is larger than ``sys.maxint``.
|
||||
|
||||
``L`` (long) [PY_LONG_LONG]
|
||||
Convert a C :ctype:`long long` to a Python long integer object. Only available
|
||||
on platforms that support :ctype:`long long`.
|
||||
Convert a C :ctype:`long long` to a Python long integer object. Only
|
||||
available on platforms that support :ctype:`long long`.
|
||||
|
||||
``K`` (long) [unsigned PY_LONG_LONG]
|
||||
Convert a C :ctype:`unsigned long long` to a Python long integer object. Only
|
||||
available on platforms that support :ctype:`unsigned long long`.
|
||||
Convert a C :ctype:`unsigned long long` to a Python long integer object.
|
||||
Only available on platforms that support :ctype:`unsigned long long`.
|
||||
|
||||
``n`` (int) [Py_ssize_t]
|
||||
Convert a C :ctype:`Py_ssize_t` to a Python integer or long integer.
|
||||
|
|
@ -488,8 +499,8 @@ and the following format units are left untouched.
|
|||
.. versionadded:: 2.5
|
||||
|
||||
``c`` (string of length 1) [char]
|
||||
Convert a C :ctype:`int` representing a character to a Python string of length
|
||||
1.
|
||||
Convert a C :ctype:`int` representing a character to a Python string of
|
||||
length 1.
|
||||
|
||||
``d`` (float) [double]
|
||||
Convert a C :ctype:`double` to a Python floating point number.
|
||||
|
|
@ -502,39 +513,41 @@ and the following format units are left untouched.
|
|||
|
||||
``O`` (object) [PyObject \*]
|
||||
Pass a Python object untouched (except for its reference count, which is
|
||||
incremented by one). If the object passed in is a *NULL* pointer, it is assumed
|
||||
that this was caused because the call producing the argument found an error and
|
||||
set an exception. Therefore, :cfunc:`Py_BuildValue` will return *NULL* but won't
|
||||
raise an exception. If no exception has been raised yet, :exc:`SystemError` is
|
||||
set.
|
||||
incremented by one). If the object passed in is a *NULL* pointer, it is
|
||||
assumed that this was caused because the call producing the argument
|
||||
found an error and set an exception. Therefore, :cfunc:`Py_BuildValue`
|
||||
will return *NULL* but won't raise an exception. If no exception has
|
||||
been raised yet, :exc:`SystemError` is set.
|
||||
|
||||
``S`` (object) [PyObject \*]
|
||||
Same as ``O``.
|
||||
|
||||
``N`` (object) [PyObject \*]
|
||||
Same as ``O``, except it doesn't increment the reference count on the object.
|
||||
Useful when the object is created by a call to an object constructor in the
|
||||
argument list.
|
||||
Same as ``O``, except it doesn't increment the reference count on the
|
||||
object. Useful when the object is created by a call to an object
|
||||
constructor in the argument list.
|
||||
|
||||
``O&`` (object) [*converter*, *anything*]
|
||||
Convert *anything* to a Python object through a *converter* function. The
|
||||
function is called with *anything* (which should be compatible with :ctype:`void
|
||||
\*`) as its argument and should return a "new" Python object, or *NULL* if an
|
||||
error occurred.
|
||||
Convert *anything* to a Python object through a *converter* function.
|
||||
The function is called with *anything* (which should be compatible with
|
||||
:ctype:`void \*`) as its argument and should return a "new" Python
|
||||
object, or *NULL* if an error occurred.
|
||||
|
||||
``(items)`` (tuple) [*matching-items*]
|
||||
Convert a sequence of C values to a Python tuple with the same number of items.
|
||||
Convert a sequence of C values to a Python tuple with the same number of
|
||||
items.
|
||||
|
||||
``[items]`` (list) [*matching-items*]
|
||||
Convert a sequence of C values to a Python list with the same number of items.
|
||||
Convert a sequence of C values to a Python list with the same number of
|
||||
items.
|
||||
|
||||
``{items}`` (dictionary) [*matching-items*]
|
||||
Convert a sequence of C values to a Python dictionary. Each pair of consecutive
|
||||
C values adds one item to the dictionary, serving as key and value,
|
||||
respectively.
|
||||
Convert a sequence of C values to a Python dictionary. Each pair of
|
||||
consecutive C values adds one item to the dictionary, serving as key and
|
||||
value, respectively.
|
||||
|
||||
If there is an error in the format string, the :exc:`SystemError` exception is
|
||||
set and *NULL* returned.
|
||||
If there is an error in the format string, the :exc:`SystemError` exception
|
||||
is set and *NULL* returned.
|
||||
|
||||
.. cfunction:: PyObject* Py_VaBuildValue(const char *format, va_list vargs)
|
||||
|
||||
|
|
|
|||
Loading…
Add table
Add a link
Reference in a new issue