https://github.com/python/cpython/commit/417c130ba55ca29e132808a0a500329f73b6ec41
commit: 417c130ba55ca29e132808a0a500329f73b6ec41
branch: main
author: Bénédikt Tran <[email protected]>
committer: encukou <[email protected]>
date: 2024-10-25T15:32:23+02:00
summary:
gh-120313: amend documentation regarding `ctypes._CFuncPtr` (GH-120989)
improve docs
files:
M Doc/library/ctypes.rst
diff --git a/Doc/library/ctypes.rst b/Doc/library/ctypes.rst
index d49959b4eb7da2..99909de20ef439 100644
--- a/Doc/library/ctypes.rst
+++ b/Doc/library/ctypes.rst
@@ -397,7 +397,7 @@ as calling functions with a fixed number of parameters. On
some platforms, and i
particular ARM64 for Apple Platforms, the calling convention for variadic
functions
is different than that for regular functions.
-On those platforms it is required to specify the :attr:`~_FuncPtr.argtypes`
+On those platforms it is required to specify the :attr:`~_CFuncPtr.argtypes`
attribute for the regular, non-variadic, function arguments:
.. code-block:: python3
@@ -405,7 +405,7 @@ attribute for the regular, non-variadic, function arguments:
libc.printf.argtypes = [ctypes.c_char_p]
Because specifying the attribute does not inhibit portability it is advised to
always
-specify :attr:`~_FuncPtr.argtypes` for all variadic functions.
+specify :attr:`~_CFuncPtr.argtypes` for all variadic functions.
.. _ctypes-calling-functions-with-own-custom-data-types:
@@ -440,9 +440,9 @@ Specifying the required argument types (function prototypes)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
It is possible to specify the required argument types of functions exported
from
-DLLs by setting the :attr:`~_FuncPtr.argtypes` attribute.
+DLLs by setting the :attr:`~_CFuncPtr.argtypes` attribute.
-:attr:`~_FuncPtr.argtypes` must be a sequence of C data types (the
:func:`!printf` function is
+:attr:`~_CFuncPtr.argtypes` must be a sequence of C data types (the
:func:`!printf` function is
probably not a good example here, because it takes a variable number and
different types of parameters depending on the format string, on the other hand
this is quite handy to experiment with this feature)::
@@ -467,7 +467,7 @@ prototype for a C function), and tries to convert the
arguments to valid types::
If you have defined your own classes which you pass to function calls, you have
to implement a :meth:`~_CData.from_param` class method for them to be able to
use them
-in the :attr:`~_FuncPtr.argtypes` sequence. The :meth:`~_CData.from_param`
class method receives
+in the :attr:`~_CFuncPtr.argtypes` sequence. The :meth:`~_CData.from_param`
class method receives
the Python object passed to the function call, it should do a typecheck or
whatever is needed to make sure this object is acceptable, and then return the
object itself, its :attr:`!_as_parameter_` attribute, or whatever you want to
@@ -490,7 +490,7 @@ Return types
By default functions are assumed to return the C :c:expr:`int` type. Other
-return types can be specified by setting the :attr:`~_FuncPtr.restype`
attribute of the
+return types can be specified by setting the :attr:`~_CFuncPtr.restype`
attribute of the
function object.
The C prototype of :c:func:`time` is ``time_t time(time_t *)``. Because
:c:type:`time_t`
@@ -499,7 +499,7 @@ specify the :attr:`!restype` attribute::
>>> libc.time.restype = c_time_t
-The argument types can be specified using :attr:`~_FuncPtr.argtypes`::
+The argument types can be specified using :attr:`~_CFuncPtr.argtypes`::
>>> libc.time.argtypes = (POINTER(c_time_t),)
@@ -522,7 +522,7 @@ a string pointer and a char, and returns a pointer to a
string::
>>>
If you want to avoid the :func:`ord("x") <ord>` calls above, you can set the
-:attr:`~_FuncPtr.argtypes` attribute, and the second argument will be
converted from a
+:attr:`~_CFuncPtr.argtypes` attribute, and the second argument will be
converted from a
single character Python bytes object into a C char:
.. doctest::
@@ -541,7 +541,7 @@ single character Python bytes object into a C char:
>>>
You can also use a callable Python object (a function or a class for example)
as
-the :attr:`~_FuncPtr.restype` attribute, if the foreign function returns an
integer. The
+the :attr:`~_CFuncPtr.restype` attribute, if the foreign function returns an
integer. The
callable will be called with the *integer* the C function returns, and the
result of this call will be used as the result of your function call. This is
useful to check for error return values and automatically raise an exception::
@@ -569,7 +569,7 @@ get the string representation of an error code, and
*returns* an exception.
:func:`GetLastError` to retrieve it.
Please note that a much more powerful error checking mechanism is available
-through the :attr:`~_FuncPtr.errcheck` attribute;
+through the :attr:`~_CFuncPtr.errcheck` attribute;
see the reference manual for details.
@@ -877,7 +877,7 @@ Type conversions
^^^^^^^^^^^^^^^^
Usually, ctypes does strict type checking. This means, if you have
-``POINTER(c_int)`` in the :attr:`~_FuncPtr.argtypes` list of a function or as
the type of
+``POINTER(c_int)`` in the :attr:`~_CFuncPtr.argtypes` list of a function or as
the type of
a member field in a structure definition, only instances of exactly the same
type are accepted. There are some exceptions to this rule, where ctypes
accepts
other objects. For example, you can pass compatible array instances instead of
@@ -898,7 +898,7 @@ pointer types. So, for ``POINTER(c_int)``, ctypes accepts
an array of c_int::
>>>
In addition, if a function argument is explicitly declared to be a pointer type
-(such as ``POINTER(c_int)``) in :attr:`~_FuncPtr.argtypes`, an object of the
pointed
+(such as ``POINTER(c_int)``) in :attr:`~_CFuncPtr.argtypes`, an object of the
pointed
type (``c_int`` in this case) can be passed to the function. ctypes will apply
the required :func:`byref` conversion in this case automatically.
@@ -1627,10 +1627,20 @@ As explained in the previous section, foreign functions
can be accessed as
attributes of loaded shared libraries. The function objects created in this
way
by default accept any number of arguments, accept any ctypes data instances as
arguments, and return the default result type specified by the library loader.
-They are instances of a private class:
+They are instances of a private local class :class:`!_FuncPtr` (not exposed
+in :mod:`!ctypes`) which inherits from the private :class:`_CFuncPtr` class:
-.. class:: _FuncPtr
+.. doctest::
+
+ >>> import ctypes
+ >>> lib = ctypes.CDLL(None)
+ >>> issubclass(lib._FuncPtr, ctypes._CFuncPtr)
+ True
+ >>> lib._FuncPtr is ctypes._CFuncPtr
+ False
+
+.. class:: _CFuncPtr
Base class for C callable foreign functions.
@@ -1796,7 +1806,7 @@ different ways, depending on the type and number of the
parameters in the call:
The optional *paramflags* parameter creates foreign function wrappers with much
more functionality than the features described above.
-*paramflags* must be a tuple of the same length as :attr:`~_FuncPtr.argtypes`.
+*paramflags* must be a tuple of the same length as :attr:`~_CFuncPtr.argtypes`.
Each item in this tuple contains further information about a parameter, it must
be a tuple containing one, two, or three items.
@@ -1867,7 +1877,7 @@ value if there is a single one, or a tuple containing the
output parameter
values when there are more than one, so the GetWindowRect function now returns
a
RECT instance, when called.
-Output parameters can be combined with the :attr:`~_FuncPtr.errcheck` protocol
to do
+Output parameters can be combined with the :attr:`~_CFuncPtr.errcheck`
protocol to do
further output processing and error checking. The win32 ``GetWindowRect`` api
function returns a ``BOOL`` to signal success or failure, so this function
could
do the error checking, and raises an exception when the api call failed::
@@ -1880,7 +1890,7 @@ do the error checking, and raises an exception when the
api call failed::
>>> GetWindowRect.errcheck = errcheck
>>>
-If the :attr:`~_FuncPtr.errcheck` function returns the argument tuple it
receives
+If the :attr:`~_CFuncPtr.errcheck` function returns the argument tuple it
receives
unchanged, :mod:`ctypes` continues the normal processing it does on the output
parameters. If you want to return a tuple of window coordinates instead of a
``RECT`` instance, you can retrieve the fields in the function and return them
@@ -2180,7 +2190,7 @@ Data types
This method adapts *obj* to a ctypes type. It is called with the actual
object used in a foreign function call when the type is present in the
- foreign function's :attr:`~_FuncPtr.argtypes` tuple;
+ foreign function's :attr:`~_CFuncPtr.argtypes` tuple;
it must return an object that can be used as a function call parameter.
All ctypes data types have a default implementation of this classmethod
@@ -2246,7 +2256,7 @@ Fundamental data types
Fundamental data types, when returned as foreign function call results, or, for
example, by retrieving structure field members or array items, are
transparently
converted to native Python types. In other words, if a foreign function has a
-:attr:`~_FuncPtr.restype` of :class:`c_char_p`, you will always receive a
Python bytes
+:attr:`~_CFuncPtr.restype` of :class:`c_char_p`, you will always receive a
Python bytes
object, *not* a :class:`c_char_p` instance.
.. XXX above is false, it actually returns a Unicode string
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