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Commit b5f4bf8c authored by Thomas Heller's avatar Thomas Heller
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New docs for ctypes.

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Doc/lib/lib.tex
View file @ b5f4bf8c
......@@ -245,7 +245,6 @@ and how to embed it in other applications.
\input{libplatform}
\input{liberrno}
\input{libctypes}
\input{libctypesref}
\input{libsomeos} % Optional Operating System Services
\input{libselect}
......
Doc/lib/libctypes.tex
View file @ b5f4bf8c
\newlength{\locallinewidth}
\ifx\locallinewidth\undefined\newlength{\locallinewidth}\fi
\setlength{\locallinewidth}{\linewidth}
\section{\module{ctypes} --- A foreign function library for Python.}
\declaremodule{standard}{ctypes}
......@@ -70,6 +70,12 @@ calling the constructor:
XXX Add section for Mac OS X.
\subsubsection{Finding shared libraries\label{ctypes-finding-shared-libraries}}
XXX Add description of ctypes.util.find{\_}library (once I really
understand it enough to describe it).
\subsubsection{Accessing functions from loaded dlls\label{ctypes-accessing-functions-from-loaded-dlls}}
Functions are accessed as attributes of dll objects:
......@@ -186,158 +192,172 @@ Before we move on calling functions with other parameter types, we
have to learn more about \code{ctypes} data types.
\subsubsection{Simple data types\label{ctypes-simple-data-types}}
\subsubsection{Fundamental data types\label{ctypes-fundamental-data-types}}
\code{ctypes} defines a number of primitive C compatible data types :
\begin{quote}
\begin{longtable}[c]{|p{0.19\locallinewidth}|p{0.28\locallinewidth}|p{0.14\locallinewidth}|}
\hline
\textbf{
\begin{tableiii}{l|l|l}{textrm}
{
ctypes type
} & \textbf{
}
{
C type
} & \textbf{
}
{
Python type
} \\
\hline
\endhead
}
\lineiii{
\class{c{\_}char}
&
}
{
\code{char}
&
}
{
character
\\
\hline
}
\lineiii{
\class{c{\_}byte}
&
}
{
\code{char}
&
}
{
integer
\\
\hline
}
\lineiii{
\class{c{\_}ubyte}
&
}
{
\code{unsigned char}
&
}
{
integer
\\
\hline
}
\lineiii{
\class{c{\_}short}
&
}
{
\code{short}
&
}
{
integer
\\
\hline
}
\lineiii{
\class{c{\_}ushort}
&
}
{
\code{unsigned short}
&
}
{
integer
\\
\hline
}
\lineiii{
\class{c{\_}int}
&
}
{
\code{int}
&
}
{
integer
\\
\hline
}
\lineiii{
\class{c{\_}uint}
&
}
{
\code{unsigned int}
&
}
{
integer
\\
\hline
}
\lineiii{
\class{c{\_}long}
&
}
{
\code{long}
&
}
{
integer
\\
\hline
}
\lineiii{
\class{c{\_}ulong}
&
}
{
\code{unsigned long}
&
}
{
long
\\
\hline
}
\lineiii{
\class{c{\_}longlong}
&
}
{
\code{{\_}{\_}int64} or
\code{long long}
&
}
{
long
\\
\hline
}
\lineiii{
\class{c{\_}ulonglong}
&
}
{
\code{unsigned {\_}{\_}int64} or
\code{unsigned long long}
&
}
{
long
\\
\hline
}
\lineiii{
\class{c{\_}float}
&
}
{
\code{float}
&
}
{
float
\\
\hline
}
\lineiii{
\class{c{\_}double}
&
}
{
\code{double}
&
}
{
float
\\
\hline
}
\lineiii{
\class{c{\_}char{\_}p}
&
}
{
\code{char *}
(NUL terminated)
&
}
{
string or
\code{None}
\\
\hline
}
\lineiii{
\class{c{\_}wchar{\_}p}
&
}
{
\code{wchar{\_}t *}
(NUL terminated)
&
}
{
unicode or
\code{None}
\\
\hline
}
\lineiii{
\class{c{\_}void{\_}p}
&
}
{
\code{void *}
&
}
{
integer or
\code{None}
\\
\hline
\end{longtable}
}
\end{tableiii}
\end{quote}
All these types can be created by calling them with an optional
......@@ -380,6 +400,7 @@ c_char_p('Hello, World')
c_char_p('Hi, there')
>>> print s # first string is unchanged
Hello, World
>>>
\end{verbatim}
You should be careful, however, not to pass them to functions
......@@ -575,7 +596,7 @@ for error return values and automatically raise an exception:
>>> GetModuleHandle.restype = ValidHandle # doctest: +WINDOWS
>>> GetModuleHandle(None) # doctest: +WINDOWS
486539264
>>> GetModuleHandle("something silly") # doctest: +WINDOWS +IGNORE_EXCEPTION_DETAIL
>>> GetModuleHandle("something silly") # doctest: +WINDOWS
Traceback (most recent call last):
File "<stdin>", line 1, in ?
File "<stdin>", line 3, in ValidHandle
......@@ -744,6 +765,7 @@ containing 4 POINTs among other stuff:
>>>
>>> print len(MyStruct().point_array)
4
>>>
\end{verbatim}
Instances are created in the usual way, by calling the class:
......@@ -772,6 +794,10 @@ Initializers of the correct type can also be specified:
\subsubsection{Pointers\label{ctypes-pointers}}
XXX Rewrite this section. Normally one only uses indexing, not the .contents
attribute!
List some recipes with pointers. bool(ptr), POINTER(tp)(), ...?
Pointer instances are created by calling the \code{pointer} function on a
\code{ctypes} type:
\begin{verbatim}
......@@ -781,16 +807,25 @@ Pointer instances are created by calling the \code{pointer} function on a
>>>
\end{verbatim}
XXX XXX Not correct: use indexing, not the contents atribute
Pointer instances have a \code{contents} attribute which returns the
ctypes' type pointed to, the \code{c{\_}int(42)} in the above case:
object to which the pointer points, the \code{i} object above:
\begin{verbatim}
>>> pi.contents
c_long(42)
>>>
\end{verbatim}
Note that \code{ctypes} does not have OOR (original object return), it
constructs a new, equivalent object each time you retrieve an
attribute:
\begin{verbatim}
>>> pi.contents is i
False
>>> pi.contents is pi.contents
False
>>>
\end{verbatim}
Assigning another \class{c{\_}int} instance to the pointer's contents
attribute would cause the pointer to point to the memory location
where this is stored:
......@@ -808,23 +843,21 @@ Pointer instances can also be indexed with integers:
>>>
\end{verbatim}
XXX What is this???
Assigning to an integer index changes the pointed to value:
\begin{verbatim}
>>> i2 = pi[0]
>>> i2
99
>>> print i
c_long(99)
>>> pi[0] = 22
>>> i2
99
>>> print i
c_long(22)
>>>
\end{verbatim}
It is also possible to use indexes different from 0, but you must know
what you're doing when you use this: You access or change arbitrary
memory locations when you do this. Generally you only use this feature
if you receive a pointer from a C function, and you \emph{know} that the
pointer actually points to an array instead of a single item.
what you're doing, just as in C: You can access or change arbitrary
memory locations. Generally you only use this feature if you receive a
pointer from a C function, and you \emph{know} that the pointer actually
points to an array instead of a single item.
\subsubsection{Pointer classes/types\label{ctypes-pointer-classestypes}}
......@@ -837,7 +870,7 @@ This is done with the \code{POINTER} function, which accepts any
>>> PI = POINTER(c_int)
>>> PI
<class 'ctypes.LP_c_long'>
>>> PI(42) # doctest: +IGNORE_EXCEPTION_DETAIL
>>> PI(42)
Traceback (most recent call last):
File "<stdin>", line 1, in ?
TypeError: expected c_long instead of int
......@@ -847,6 +880,82 @@ TypeError: expected c_long instead of int
\end{verbatim}
\subsubsection{Type conversions\label{ctypes-type-conversions}}
Usually, ctypes does strict type checking. This means, if you have
\code{POINTER(c{\_}int)} in the \member{argtypes} list of a function or in the
\member{{\_}fields{\_}} of 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 pointer types. So, for \code{POINTER(c{\_}int)},
ctypes accepts an array of c{\_}int values:
\begin{verbatim}
>>> class Bar(Structure):
... _fields_ = [("count", c_int), ("values", POINTER(c_int))]
...
>>> bar = Bar()
>>> print bar._objects
None
>>> bar.values = (c_int * 3)(1, 2, 3)
>>> print bar._objects
{'1': ({}, <ctypes._endian.c_long_Array_3 object at ...>)}
>>> bar.count = 3
>>> for i in range(bar.count):
... print bar.values[i]
...
1
2
3
>>>
\end{verbatim}
To set a POINTER type field to \code{NULL}, you can assign \code{None}:
\begin{verbatim}
>>> bar.values = None
>>>
\end{verbatim}
XXX list other conversions...
Sometimes you have instances of incompatible types. In \code{C}, you can
cast one type into another type. \code{ctypes} provides a \code{cast}
function which can be used in the same way. The Bar structure defined
above accepts \code{POINTER(c{\_}int)} pointers or \class{c{\_}int} arrays for its
\code{values} field, but not instances of other types:
\begin{verbatim}
>>> bar.values = (c_byte * 4)()
Traceback (most recent call last):
File "<stdin>", line 1, in ?
TypeError: incompatible types, c_byte_Array_4 instance instead of LP_c_long instance
>>>
\end{verbatim}
For these cases, the \code{cast} function is handy.
The \code{cast} function can be used to cast a ctypes instance into a
pointer to a different ctypes data type. \code{cast} takes two
parameters, a ctypes object that is or can be converted to a pointer
of some kind, and a ctypes pointer type. It returns an instance of
the second argument, which references the same memory block as the
first argument:
\begin{verbatim}
>>> a = (c_byte * 4)()
>>> cast(a, POINTER(c_int))
<ctypes.LP_c_long object at ...>
>>>
\end{verbatim}
So, \code{cast} can be used to assign to the \code{values} field of \code{Bar}
the structure:
\begin{verbatim}
>>> bar = Bar()
>>> bar.values = cast((c_byte * 4)(), POINTER(c_int))
>>> print bar.values[0]
0
>>>
\end{verbatim}
\subsubsection{Incomplete Types\label{ctypes-incomplete-types}}
\emph{Incomplete Types} are structures, unions or arrays whose members are
......@@ -1175,6 +1284,7 @@ Consider the following example:
>>> rc.a, rc.b = rc.b, rc.a
>>> print rc.a.x, rc.a.y, rc.b.x, rc.b.y
3 4 3 4
>>>
\end{verbatim}
Hm. We certainly expected the last statement to print \code{3 4 1 2}.
......@@ -1184,6 +1294,7 @@ line above:
>>> temp0, temp1 = rc.b, rc.a
>>> rc.a = temp0
>>> rc.b = temp1
>>>
\end{verbatim}
Note that \code{temp0} and \code{temp1} are objects still using the internal
......@@ -1214,6 +1325,80 @@ the object itself, instead the \code{contents} of the object is stored.
Accessing the contents again constructs a new Python each time!
\subsubsection{Variable-sized data types\label{ctypes-variable-sized-data-types}}
\code{ctypes} provides some support for variable-sized arrays and
structures (this was added in version 0.9.9.7).
The \code{resize} function can be used to resize the memory buffer of an
existing ctypes object. The function takes the object as first
argument, and the requested size in bytes as the second argument. The
memory block cannot be made smaller than the natural memory block
specified by the objects type, a \code{ValueError} is raised if this is
tried:
\begin{verbatim}
>>> short_array = (c_short * 4)()
>>> print sizeof(short_array)
8
>>> resize(short_array, 4)
Traceback (most recent call last):
...
ValueError: minimum size is 8
>>> resize(short_array, 32)
>>> sizeof(short_array)
32
>>> sizeof(type(short_array))
8
>>>
\end{verbatim}
This is nice and fine, but how would one access the additional
elements contained in this array? Since the type still only knows
about 4 elements, we get errors accessing other elements:
\begin{verbatim}
>>> short_array[:]
[0, 0, 0, 0]
>>> short_array[7]
Traceback (most recent call last):
...
IndexError: invalid index
>>>
\end{verbatim}
The solution is to use 1-element arrays; as a special case ctypes does
no bounds checking on them:
\begin{verbatim}
>>> short_array = (c_short * 1)()
>>> print sizeof(short_array)
2
>>> resize(short_array, 32)
>>> sizeof(short_array)
32
>>> sizeof(type(short_array))
2
>>> short_array[0:8]
[0, 0, 0, 0, 0, 0, 0, 0]
>>> short_array[7] = 42
>>> short_array[0:8]
[0, 0, 0, 0, 0, 0, 0, 42]
>>>
\end{verbatim}
Using 1-element arrays as variable sized fields in structures works as
well, but they should be used as the last field in the structure
definition. This example shows a definition from the Windows header
files:
\begin{verbatim}
class SP_DEVICE_INTERFACE_DETAIL_DATA(Structure):
_fields_ = [("cbSize", c_int),
("DevicePath", c_char * 1)]
\end{verbatim}
Another way to use variable-sized data types with \code{ctypes} is to use
the dynamic nature of Python, and (re-)define the data type after the
required size is already known, on a case by case basis.
\subsubsection{Bugs, ToDo and non-implemented things\label{ctypes-bugs-todo-non-implemented-things}}
Enumeration types are not implemented. You can do it easily yourself,
......@@ -1224,3 +1409,636 @@ using \class{c{\_}int} as the base class.
% compile-command: "make.bat"
% End:
\subsection{ctypes reference\label{ctypes-ctypes-reference}}
\subsubsection{Loading shared libraries\label{ctypes-loading-shared-libraries}}
\begin{classdesc}{LibraryLoader}{dlltype}
Class which loads shared libraries.
\end{classdesc}
\begin{methoddesc}{LoadLibrary}{name, mode=RTLD_LOCAL, handle=None}
Load a shared library.
\end{methoddesc}
\begin{classdesc}{CDLL}{name, mode=RTLD_LOCAL, handle=None}
XXX
\end{classdesc}
\begin{datadescni}{cdll}
XXX
\end{datadescni}
\begin{funcdesc}{OleDLL}{name, mode=RTLD_LOCAL, handle=None}
XXX
\end{funcdesc}
\begin{datadescni}{oledll}
XXX
\end{datadescni}
\begin{classdesc*}{py_object}
XXX
\end{classdesc*}
\begin{funcdesc}{PyDLL}{name, mode=RTLD_LOCAL, handle=None}
XXX
\end{funcdesc}
\begin{datadescni}{pydll}
XXX
\end{datadescni}
\begin{datadescni}{RTLD_GLOBAL}
XXX
\end{datadescni}
\begin{datadescni}{RTLD_LOCAL}
XXX
\end{datadescni}
\begin{funcdesc}{WinDLL}{name, mode=RTLD_LOCAL, handle=None}
XXX
\end{funcdesc}
\begin{datadescni}{windll}
XXX
\end{datadescni}
\begin{datadescni}{pythonapi()}
XXX
\end{datadescni}
\subsubsection{Foreign functions\label{ctypes-foreign-functions}}
The ultimate goal of \code{ctypes} is to call functions in shared
libraries, aka as foreign functions. Foreign function instances can
be created by retrieving them as attributes of loaded shared
libraries, or by instantiating a \emph{function prototype}.
By default, functions got as attributes of loaded shared libraries
accept any arguments, and have a return type of \class{c{\_}int}.
Function prototypes are created by factory functions.
They are created by calling one of the following factory functions:
\begin{funcdesc}{CFUNCTYPE}{restype, *argtypes}
This is a factory function that returns a function prototype. The
function prototype describes a function that has a result type of
\member{restype}, and accepts arguments as specified by
\member{argtypes}. The function prototype can be used to construct
several kinds of functions, depending on how the prototype is
called.
The prototypes returned by \function{CFUNCTYPE} or \code{PYFUNCTYPE} create
functions that use the standard C calling convention, prototypes
returned from \function{WINFUNCTYPE} (on Windows) use the \code{{\_}{\_}stdcall}
calling convention.
Functions created by calling the \function{CFUNCTYPE} and \function{WINFUNCTYPE}
prototypes release the Python GIL before entering the foreign
function, and acquire it back after leaving the function code.
\end{funcdesc}
\begin{funcdesc}{WINFUNCTYPE}{restype, *argtypes}
TBD
\end{funcdesc}
\begin{funcdesc}{PYFUNCTYPE}{restype, *argtypes}
TBD
\end{funcdesc}
\begin{excdesc}{ArgumentError()}
This exception is raised when a foreign function call cannot
convert one of the passed arguments.
\end{excdesc}
\subsubsection{Utility functions\label{ctypes-utility-functions}}
\begin{funcdesc}{addressof}{obj}
Returns the address of the memory buffer as integer. \code{obj} must
be an instance of a ctypes type.
\end{funcdesc}
\begin{funcdesc}{alignment}{obj_or_type}
Returns the alignment requirements of a ctypes type.
\code{obj{\_}or{\_}type} must be a ctypes type or instance.
\end{funcdesc}
\begin{funcdesc}{byref}{obj}
Returns a light-weight pointer to \code{obj}, which must be an
instance of a ctypes type. The returned object can only be used as
a foreign function call parameter. It behaves similar to
\code{pointer(obj)}, but the construction is a lot faster.
\end{funcdesc}
\begin{funcdesc}{cast}{obj, type}
This function is similar to the cast operator in C. It returns a
new instance of \code{type} which points to the same memory block as
\code{obj}. \code{type} must be a pointer type, and \code{obj} must be an
object that can be interpreted as a pointer.
\end{funcdesc}
\begin{funcdesc}{create_string_buffer}{init_or_size\optional{, size}}
This function creates a mutable character buffer. The returned
object is a ctypes array of \class{c{\_}char}.
\code{init{\_}or{\_}size} must be an integer which specifies the size of
the array, or a string which will be used to initialize the array
items.
If a string is specified as first argument, the buffer is made one
item larger than the length of the string so that the last element
in the array is a NUL termination character. An integer can be
passed as second argument which allows to specify the size of the
array if the length of the string should not be used.
If the first parameter is a unicode string, it is converted into
an 8-bit string according to ctypes conversion rules.
\end{funcdesc}
\begin{funcdesc}{create_unicode_buffer}{init_or_size\optional{, size}}
This function creates a mutable unicode character buffer. The
returned object is a ctypes array of \class{c{\_}wchar}.
\code{init{\_}or{\_}size} must be an integer which specifies the size of
the array, or a unicode string which will be used to initialize
the array items.
If a unicode string is specified as first argument, the buffer is
made one item larger than the length of the string so that the
last element in the array is a NUL termination character. An
integer can be passed as second argument which allows to specify
the size of the array if the length of the string should not be
used.
If the first parameter is a 8-bit string, it is converted into an
unicode string according to ctypes conversion rules.
\end{funcdesc}
\begin{funcdesc}{DllCanUnloadNow}{}
Windows only: This function is a hook which allows to implement
inprocess COM servers with ctypes. It is called from the
DllCanUnloadNow function that the {\_}ctypes extension dll exports.
\end{funcdesc}
\begin{funcdesc}{DllGetClassObject}{}
Windows only: This function is a hook which allows to implement
inprocess COM servers with ctypes. It is called from the
DllGetClassObject function that the \code{{\_}ctypes} extension dll exports.
\end{funcdesc}
\begin{funcdesc}{FormatError}{\optional{code}}
Windows only: Returns a textual description of the error code. If
no error code is specified, the last error code is used by calling
the Windows api function GetLastError.
\end{funcdesc}
\begin{funcdesc}{GetLastError}{}
Windows only: Returns the last error code set by Windows in the
calling thread.
\end{funcdesc}
\begin{funcdesc}{memmove}{dst, src, count}
Same as the standard C memmove library function: copies \var{count}
bytes from \code{src} to \var{dst}. \var{dst} and \code{src} must be
integers or ctypes instances that can be converted to pointers.
\end{funcdesc}
\begin{funcdesc}{memset}{dst, c, count}
Same as the standard C memset library function: fills the memory
block at address \var{dst} with \var{count} bytes of value
\var{c}. \var{dst} must be an integer specifying an address, or a
ctypes instance.
\end{funcdesc}
\begin{funcdesc}{POINTER}{type}
This factory function creates and returns a new ctypes pointer
type. Pointer types are cached an reused internally, so calling
this function repeatedly is cheap. type must be a ctypes type.
\end{funcdesc}
\begin{funcdesc}{pointer}{obj}
This function creates a new pointer instance, pointing to
\code{obj}. The returned object is of the type POINTER(type(obj)).
Note: If you just want to pass a pointer to an object to a foreign
function call, you should use \code{byref(obj)} which is much faster.
\end{funcdesc}
\begin{funcdesc}{resize}{obj, size}
This function resizes the internal memory buffer of obj, which
must be an instance of a ctypes type. It is not possible to make
the buffer smaller than the native size of the objects type, as
given by sizeof(type(obj)), but it is possible to enlarge the
buffer.
\end{funcdesc}
\begin{funcdesc}{set_conversion_mode}{encoding, errors}
This function sets the rules that ctypes objects use when
converting between 8-bit strings and unicode strings. encoding
must be a string specifying an encoding, like \code{'utf-8'} or
\code{'mbcs'}, errors must be a string specifying the error handling
on encoding/decoding errors. Examples of possible values are
\code{"strict"}, \code{"replace"}, or \code{"ignore"}.
set{\_}conversion{\_}mode returns a 2-tuple containing the previous
conversion rules. On windows, the initial conversion rules are
\code{('mbcs', 'ignore')}, on other systems \code{('ascii', 'strict')}.
\end{funcdesc}
\begin{funcdesc}{sizeof}{obj_or_type}
Returns the size in bytes of a ctypes type or instance memory
buffer. Does the same as the C \code{sizeof()} function.
\end{funcdesc}
\begin{funcdesc}{string_at}{address\optional{, size}}
This function returns the string starting at memory address
address. If size is specified, it is used as size, otherwise the
string is assumed to be zero-terminated.
\end{funcdesc}
\begin{funcdesc}{WinError}{code=None, descr=None}
Windows only: this function is probably the worst-named thing in
ctypes. It creates an instance of WindowsError. If \var{code} is not
specified, \code{GetLastError} is called to determine the error
code. If \code{descr} is not spcified, \function{FormatError} is called to
get a textual description of the error.
\end{funcdesc}
\begin{funcdesc}{wstring_at}{address}
This function returns the wide character string starting at memory
address \code{address} as unicode string. If \code{size} is specified,
it is used as the number of characters of the string, otherwise
the string is assumed to be zero-terminated.
\end{funcdesc}
\subsubsection{Data types\label{ctypes-data-types}}
\begin{classdesc*}{_CData}
This non-public class is the common base class of all ctypes data
types. Among other things, all ctypes type instances contain a
memory block that hold C compatible data; the address of the
memory block is returned by the \code{addressof()} helper function.
Another instance variable is exposed as \member{{\_}objects}; this
contains other Python objects that need to be kept alive in case
the memory block contains pointers.
\end{classdesc*}
Common methods of ctypes data types, these are all class methods (to
be exact, they are methods of the metaclass):
\begin{methoddesc}{from_address}{address}
This method returns a ctypes type instance using the memory
specified by address.
\end{methoddesc}
\begin{methoddesc}{from_param}{obj}
This method adapts obj to a ctypes type.
\end{methoddesc}
\begin{methoddesc}{in_dll}{name, library}
This method returns a ctypes type instance exported by a shared
library. \var{name} is the name of the symbol that exports the data,
\code{library} is the loaded shared library.
\end{methoddesc}
Common instance variables of ctypes data types:
\begin{memberdesc}{_b_base_}
Sometimes ctypes data instances do not own the memory block they
contain, instead they share part of the memory block of a base
object. The \member{{\_}b{\_}base{\_}} readonly member is the root ctypes
object that owns the memory block.
\end{memberdesc}
\begin{memberdesc}{_b_needsfree_}
This readonly variable is true when the ctypes data instance has
allocated the memory block itself, false otherwise.
\end{memberdesc}
\begin{memberdesc}{_objects}
This member is either \code{None} or a dictionary containing Python
objects that need to be kept alive so that the memory block
contents is kept valid. This object is only exposed for
debugging; never modify the contents of this dictionary.
\end{memberdesc}
\subsubsection{Fundamental data types\label{ctypes-fundamental-data-types}}
\begin{classdesc*}{_SimpleCData}
This non-public class is the base class of all fundamental ctypes
data types. It is mentioned here because it contains the common
attributes of the fundamental ctypes data types. \code{{\_}SimpleCData}
is a subclass of \code{{\_}CData}, so it inherits their methods and
attributes.
\end{classdesc*}
Instances have a single attribute:
\begin{memberdesc}{value}
This attribute contains the actual value of the instance. For
integer and pointer types, it is an integer, for character types,
it is a single character string, for character pointer types it
is a Python string or unicode string.
When the \code{value} attribute is retrieved from a ctypes instance,
usually a new object is returned each time. \code{ctypes} does \emph{not}
implement original object return, always a new object is
constructed. The same is true for all other ctypes object
instances.
\end{memberdesc}
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 \member{restype} of \class{c{\_}char{\_}p},
you will always receive a Python string, \emph{not} a \class{c{\_}char{\_}p}
instance.
Subclasses of fundamental data types do \emph{not} inherit this behaviour.
So, if a foreign functions \member{restype} is a subclass of \class{c{\_}void{\_}p},
you will receive an instance of this subclass from the function call.
Of course, you can get the value of the pointer by accessing the
\code{value} attribute.
These are the fundamental ctypes data types:
\begin{classdesc*}{c_byte}
Represents the C signed char datatype, and interprets the value as
small integer. The constructor accepts an optional integer
initializer; no overflow checking is done.
\end{classdesc*}
\begin{classdesc*}{c_char}
Represents the C char datatype, and interprets the value as a single
character. The constructor accepts an optional string initializer,
the length of the string must be exactly one character.
\end{classdesc*}
\begin{classdesc*}{c_char_p}
Represents the C char * datatype, which must be a pointer to a
zero-terminated string. The constructor accepts an integer
address, or a string.
\end{classdesc*}
\begin{classdesc*}{c_double}
Represents the C double datatype. The constructor accepts an
optional float initializer.
\end{classdesc*}
\begin{classdesc*}{c_float}
Represents the C double datatype. The constructor accepts an
optional float initializer.
\end{classdesc*}
\begin{classdesc*}{c_int}
Represents the C signed int datatype. The constructor accepts an
optional integer initializer; no overflow checking is done. On
platforms where \code{sizeof(int) == sizeof(long)} it is an alias to
\class{c{\_}long}.
\end{classdesc*}
\begin{classdesc*}{c_int8}
Represents the C 8-bit \code{signed int} datatype. Usually an alias for
\class{c{\_}byte}.
\end{classdesc*}
\begin{classdesc*}{c_int16}
Represents the C 16-bit signed int datatype. Usually an alias for
\class{c{\_}short}.
\end{classdesc*}
\begin{classdesc*}{c_int32}
Represents the C 32-bit signed int datatype. Usually an alias for
\class{c{\_}int}.
\end{classdesc*}
\begin{classdesc*}{c_int64}
Represents the C 64-bit \code{signed int} datatype. Usually an alias
for \class{c{\_}longlong}.
\end{classdesc*}
\begin{classdesc*}{c_long}
Represents the C \code{signed long} datatype. The constructor accepts an
optional integer initializer; no overflow checking is done.
\end{classdesc*}
\begin{classdesc*}{c_longlong}
Represents the C \code{signed long long} datatype. The constructor accepts
an optional integer initializer; no overflow checking is done.
\end{classdesc*}
\begin{classdesc*}{c_short}
Represents the C \code{signed short} datatype. The constructor accepts an
optional integer initializer; no overflow checking is done.
\end{classdesc*}
\begin{classdesc*}{c_size_t}
Represents the C \code{size{\_}t} datatype.
\end{classdesc*}
\begin{classdesc*}{c_ubyte}
Represents the C \code{unsigned char} datatype, it interprets the
value as small integer. The constructor accepts an optional
integer initializer; no overflow checking is done.
\end{classdesc*}
\begin{classdesc*}{c_uint}
Represents the C \code{unsigned int} datatype. The constructor accepts an
optional integer initializer; no overflow checking is done. On
platforms where \code{sizeof(int) == sizeof(long)} it is an alias for
\class{c{\_}ulong}.
\end{classdesc*}
\begin{classdesc*}{c_uint8}
Represents the C 8-bit unsigned int datatype. Usually an alias for
\class{c{\_}ubyte}.
\end{classdesc*}
\begin{classdesc*}{c_uint16}
Represents the C 16-bit unsigned int datatype. Usually an alias for
\class{c{\_}ushort}.
\end{classdesc*}
\begin{classdesc*}{c_uint32}
Represents the C 32-bit unsigned int datatype. Usually an alias for
\class{c{\_}uint}.
\end{classdesc*}
\begin{classdesc*}{c_uint64}
Represents the C 64-bit unsigned int datatype. Usually an alias for
\class{c{\_}ulonglong}.
\end{classdesc*}
\begin{classdesc*}{c_ulong}
Represents the C \code{unsigned long} datatype. The constructor accepts an
optional integer initializer; no overflow checking is done.
\end{classdesc*}
\begin{classdesc*}{c_ulonglong}
Represents the C \code{unsigned long long} datatype. The constructor
accepts an optional integer initializer; no overflow checking is
done.
\end{classdesc*}
\begin{classdesc*}{c_ushort}
Represents the C \code{unsigned short} datatype. The constructor accepts an
optional integer initializer; no overflow checking is done.
\end{classdesc*}
\begin{classdesc*}{c_void_p}
Represents the C \code{void *} type. The value is represented as
integer. The constructor accepts an optional integer initializer.
\end{classdesc*}
\begin{classdesc*}{c_wchar}
Represents the C \code{wchar{\_}t} datatype, and interprets the value as a
single character unicode string. The constructor accepts an
optional string initializer, the length of the string must be
exactly one character.
\end{classdesc*}
\begin{classdesc*}{c_wchar_p}
Represents the C \code{wchar{\_}t *} datatype, which must be a pointer to
a zero-terminated wide character string. The constructor accepts
an integer address, or a string.
\end{classdesc*}
\begin{classdesc*}{HRESULT}
Windows only: Represents a \class{HRESULT} value, which contains success
or error information for a function or method call.
\end{classdesc*}
\subsubsection{Structured data types\label{ctypes-structured-data-types}}
\begin{classdesc}{Union}{*args, **kw}
Abstract base class for unions in native byte order.
\end{classdesc}
\begin{classdesc}{BigEndianStructure}{*args, **kw}
Abstract base class for structures in \emph{big endian} byte order.
\end{classdesc}
\begin{classdesc}{LittleEndianStructure}{*args, **kw}
Abstract base class for structures in \emph{little endian} byte order.
\end{classdesc}
Structures with non-native byte order cannot contain pointer type
fields, or any other data types containing pointer type fields.
\begin{classdesc}{Structure}{*args, **kw}
Abstract base class for structures in \emph{native} byte order.
\end{classdesc}
Concrete structure and union types must be created by subclassing one
of these types, and at least define a \member{{\_}fields{\_}} class variable.
\code{ctypes} will create descriptors which allow reading and writing the
fields by direct attribute accesses. These are the
\begin{memberdesc}{_fields_}
A sequence defining the structure fields. The items must be
2-tuples or 3-tuples. The first item is the name of the field,
the second item specifies the type of the field; it can be any
ctypes data type.
For integer type fields, a third optional item can be given. It
must be a small positive integer defining the bit width of the
field.
Field names must be unique within one structure or union. This is
not checked, only one field can be accessed when names are
repeated.
It is possible to define the \member{{\_}fields{\_}} class variable \emph{after}
the class statement that defines the Structure subclass, this
allows to create data types that directly or indirectly reference
themselves:
\begin{verbatim}
class List(Structure):
pass
List._fields_ = [("pnext", POINTER(List)),
...
]
\end{verbatim}
The \member{{\_}fields{\_}} class variable must, however, be defined before
the type is first used (an instance is created, \code{sizeof()} is
called on it, and so on). Later assignments to the \member{{\_}fields{\_}}
class variable will raise an AttributeError.
Structure and union subclass constructors accept both positional
and named arguments. Positional arguments are used to initialize
the fields in the same order as they appear in the \member{{\_}fields{\_}}
definition, named arguments are used to initialize the fields with
the corresponding name.
It is possible to defined sub-subclasses of structure types, they
inherit the fields of the base class plus the \member{{\_}fields{\_}} defined
in the sub-subclass, if any.
\end{memberdesc}
\begin{memberdesc}{_pack_}
An optional small integer that allows to override the alignment of
structure fields in the instance. \member{{\_}pack{\_}} must already be
defined when \member{{\_}fields{\_}} is assigned, otherwise it will have no
effect.
\end{memberdesc}
\begin{memberdesc}{_anonymous_}
An optional sequence that lists the names of unnamed (anonymous)
fields. \code{{\_}anonymous{\_}} must be already defined when \member{{\_}fields{\_}}
is assigned, otherwise it will have no effect.
The fields listed in this variable must be structure or union type
fields. \code{ctypes} will create descriptors in the structure type
that allows to access the nested fields directly, without the need
to create the structure or union field.
Here is an example type (Windows):
\begin{verbatim}
class _U(Union):
_fields_ = [("lptdesc", POINTER(TYPEDESC)),
("lpadesc", POINTER(ARRAYDESC)),
("hreftype", HREFTYPE)]
class TYPEDESC(Structure):
_fields_ = [("u", _U),
("vt", VARTYPE)]
_anonymous_ = ("u",)
\end{verbatim}
The \code{TYPEDESC} structure describes a COM data type, the \code{vt}
field specifies which one of the union fields is valid. Since the
\code{u} field is defined as anonymous field, it is now possible to
access the members directly off the TYPEDESC instance.
\code{td.lptdesc} and \code{td.u.lptdesc} are equivalent, but the former
is faster since it does not need to create a temporary \code{{\_}U}
instance:
\begin{verbatim}
td = TYPEDESC()
td.vt = VT_PTR
td.lptdesc = POINTER(some_type)
td.u.lptdesc = POINTER(some_type)
\end{verbatim}
\end{memberdesc}
It is possible to defined sub-subclasses of structures, they inherit
the fields of the base class. If the subclass definition has a
separate``{\_}fields{\_}`` variable, the fields specified in this are
appended to the fields of the base class.
\subsubsection{Arrays and pointers\label{ctypes-arrays-pointers}}
XXX
Doc/lib/libctypesref.tex deleted 100644 → 0
View file @ 7e8f10aa
\subsection{ctypes reference\label{ctypes-reference}}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% functions
\subsubsection{ctypes functions}
\begin{funcdesc}{addressof}{obj}
Returns the address of the memory buffer as integer. \var{obj} must
be an instance of a ctypes type.
\end{funcdesc}
\begin{funcdesc}{alignment}{obj_or_type}
Returns the alignment requirements of a ctypes type.
\var{obj_or_type} must be a ctypes type or an instance.
\end{funcdesc}
\begin{excclassdesc}{ArgumentError}{}
This exception is raised when a foreign function call cannot convert
one of the passed arguments.
\end{excclassdesc}
\begin{funcdesc}{byref}{obj}
Returns a light-weight pointer to \var{obj}, which must be an instance
of a ctypes type. The returned object can only be used as a foreign
function call parameter. It behaves similar to \code{pointer(obj)},
but the construction is a lot faster.
\end{funcdesc}
\begin{funcdesc}{cast}{obj, type}
This function is similar to the cast operator in C. It returns a new
instance of \var{type} which points to the same memory block as
\code{obj}. \code{type} must be a pointer type, and \code{obj}
must be an object that can be interpreted as a pointer.
\end{funcdesc}
% XXX separate section for CFUNCTYPE, WINFUNCTYPE, PYFUNCTYPE?
\begin{funcdesc}{CFUNCTYPE}{restype, *argtypes}
This is a factory function that returns a function prototype. The
function prototype describes a function that has a result type of
\code{restype}, and accepts arguments as specified by \code{argtypes}.
The function prototype can be used to construct several kinds of
functions, depending on how the prototype is called.
The prototypes returned by \code{CFUNCTYPE} or \code{PYFUNCTYPE}
create functions that use the standard C calling convention,
prototypes returned from \code{WINFUNCTYPE} (on Windows) use the
\code{__stdcall} calling convention.
Functions created by calling the \code{CFUNCTYPE} and
\code{WINFUNCTYPE} prototypes release the Python GIL
before entering the foreign function, and acquire it back after
leaving the function code.
% XXX differences between CFUNCTYPE / WINFUNCTYPE / PYFUNCTYPE
\end{funcdesc}
\begin{funcdesc}{create_string_buffer}{init_or_size\optional{, size}}
This function creates a mutable character buffer. The returned object
is a ctypes array of \code{c_char}.
\var{init_or_size} must be an integer which specifies the size of the
array, or a string which will be used to initialize the array items.
If a string is specified as first argument, the buffer is made one
item larger than the length of the string so that the last element in
the array is a NUL termination character. An integer can be passed as
second argument which allows to specify the size of the array if the
length of the string should not be used.
If the first parameter is a unicode string, it is converted into an
8-bit string according to ctypes conversion rules.
\end{funcdesc}
\begin{funcdesc}{create_unicode_buffer}{init_or_size\optional{, size}}
This function creates a mutable unicode character buffer. The
returned object is a ctypes array of \code{c_wchar}.
\var{init_or_size} must be an integer which specifies the size of the
array, or a unicode string which will be used to initialize the array
items.
If a unicode string is specified as first argument, the buffer is made
one item larger than the length of the string so that the last element
in the array is a NUL termination character. An integer can be passed
as second argument which allows to specify the size of the array if
the length of the string should not be used.
If the first parameter is a 8-bit string, it is converted into an
unicode string according to ctypes conversion rules.
\end{funcdesc}
\begin{funcdesc}{DllCanUnloadNow}{}
Windows only: This function is a hook which allows to implement
inprocess COM servers with ctypes. It is called from the
\code{DllCanUnloadNow} function that the \code{_ctypes}
extension dll exports.
\end{funcdesc}
\begin{funcdesc}{DllGetClassObject}{}
Windows only: This function is a hook which allows to implement
inprocess COM servers with ctypes. It is called from the
\code{DllGetClassObject} function that the \code{_ctypes}
extension dll exports.
\end{funcdesc}
\begin{funcdesc}{FormatError}{\optional{code}}
Windows only: Returns a textual description of the error code. If no
error code is specified, the last error code is used by calling the
Windows api function \code{GetLastError}.
\end{funcdesc}
\begin{funcdesc}{GetLastError}{}
Windows only: Returns the last error code set by Windows in the
calling thread.
\end{funcdesc}
\begin{funcdesc}{memmove}{dst, src, count}
Same as the standard C \code{memmove} library function: copies
\var{count} bytes from \code{src} to \code{dst}. \code{dst} and
\code{src} must be integers or ctypes instances that can be converted to pointers.
\end{funcdesc}
\begin{funcdesc}{memset}{dst, c, count}
Same as the standard C \code{memset} library function: fills the
memory clock at address \code{dst} with \var{count} bytes of value
\var{c}. \var{dst} must be an integer specifying an address, or a ctypes instance.
\end{funcdesc}
\begin{funcdesc}{POINTER}{type}
This factory function creates and returns a new ctypes pointer type.
Pointer types are cached an reused internally, so calling this
function repeatedly is cheap. \var{type} must be a ctypes type.
\end{funcdesc}
\begin{funcdesc}{pointer}{obj}
This function creates a new pointer instance, pointing to \var{obj}.
The returned object is of the type \code{POINTER(type(obj))}.
Note: If you just want to pass a pointer to an object to a foreign
function call, you should use \code{byref(obj)} which is much faster.
\end{funcdesc}
\begin{funcdesc}{PYFUNCTYPE}{restype, *argtypes}
\end{funcdesc}
\begin{funcdesc}{pythonapi}{}
\end{funcdesc}
\begin{funcdesc}{resize}{obj, size}
This function resizes the internal memory buffer of \var{obj}, which
must be an instance of a ctypes type. It is not possible to make the
buffer smaller than the native size of the objects type, as given by
\code{sizeof(type(obj))}, but it is possible to enlarge the buffer.
\end{funcdesc}
\begin{funcdesc}{set_conversion_mode}{encoding, errors}
This function sets the rules that ctypes objects use when converting
between 8-bit strings and unicode strings. \var{encoding} must be a
string specifying an encoding, like 'utf-8' or 'mbcs', \var{errors}
must be a string specifying the error handling on encoding/decoding
errors. Examples of possible values are ``strict'', ``replace'', or
``ignore''.
\code{set_conversion_mode} returns a 2-tuple containing the previous
conversion rules. On windows, the initial conversion rules are
\code{('mbcs', 'ignore')}, on other systems \code{('ascii', 'strict')}.
\end{funcdesc}
\begin{funcdesc}{sizeof}{obj_or_type}
Returns the size in bytes of a ctypes type or instance memory buffer.
Does the same as the C sizeof() function.
\end{funcdesc}
\begin{funcdesc}{string_at}{address\optional{size}}
This function returns the string starting at memory address
\var{address}. If \var{size} is specified, it is used as size,
otherwise the string is assumed to be zero-terminated.
\end{funcdesc}
\begin{funcdesc}{WinError}{code=None, descr=None}
Windows only: this function is probably the worst-named thing in
ctypes. It creates an instance of \code{WindowsError}. If \var{code}
is not specified, \code{GetLastError} is called to determine the error
code. If \var{descr} is not spcified, \var{FormatError} is called to
get a textual description of the error.
\end{funcdesc}
\begin{funcdesc}{WINFUNCTYPE}{restype, *argtypes}
\end{funcdesc}
\begin{funcdesc}{wstring_at}{address}
This function returns the wide character string starting at memory
address \var{address} as unicode string. If \var{size} is specified,
it is used as size, otherwise the string is assumed to be
zero-terminated.
\end{funcdesc}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% data types
\subsubsection{data types}
ctypes defines a lot of C compatible datatypes, and also allows to
define your own types. Among other things, a ctypes type instance
holds a memory block that contains C compatible data.
\begin{classdesc}{_ctypes._CData}{}
This non-public class is the base class of all ctypes data types. It
is mentioned here because it contains the common methods of the ctypes
data types.
\end{classdesc}
Common methods of ctypes data types, these are all class methods (to
be exact, they are methods of the metaclass):
\begin{methoddesc}{from_address}{address}
This method returns a ctypes type instance using the memory specified
by \code{address}.
\end{methoddesc}
\begin{methoddesc}{from_param}{obj}
This method adapts \code{obj} to a ctypes type.
\end{methoddesc}
\begin{methoddesc}{in_dll}{name, library}
This method returns a ctypes type instance exported by a shared
library. \var{name} is the name of the symbol that exports the data,
\var{library} is the loaded shared library.
\end{methoddesc}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% simple data types
\subsubsection{simple data types}
\begin{classdesc}{_ctypes._SimpleCData}{}
This non-public class is the base class of all ctypes data types. It
is mentioned here because it contains the common attributes of the
ctypes data types.
\end{classdesc}
\begin{memberdesc}{value}
This attribute contains the actual value of the instance. For integer
types, it is an integer.
\end{memberdesc}
Here are the simple ctypes data types:
\begin{classdesc}{c_byte}{\optional{value}}
Represents a C \code{signed char} datatype, and interprets the value
as small integer. The constructor accepts an optional integer
initializer; no overflow checking is done.
\end{classdesc}
\begin{classdesc}{c_char}{\optional{value}}
Represents a C \code{char} datatype, and interprets the value as a
single character. The constructor accepts an optional string
initializer, the length of the string must be exactly one character.
\end{classdesc}
\begin{classdesc}{c_char_p}{\optional{value}}
Represents a C \code{char *} datatype, which must be a pointer to a
zero-terminated string. The constructor accepts an integer address,
or a string.
% XXX Explain the difference to POINTER(c_char)
\end{classdesc}
\begin{classdesc}{c_double}{\optional{value}}
Represents a C \code{double} datatype. The constructor accepts an
optional float initializer.
\end{classdesc}
\begin{classdesc}{c_float}{\optional{value}}
Represents a C \code{double} datatype. The constructor accepts an
optional float initializer.
\end{classdesc}
\begin{classdesc}{c_int}{\optional{value}}
Represents a C \code{signed int} datatype. The constructor accepts an
optional integer initializer; no overflow checking is done. On
platforms where \code{sizeof(int) == sizeof(long)} \var{c_int} is an
alias to \var{c_long}.
\end{classdesc}
\begin{classdesc}{c_int16}{\optional{value}}
Represents a C 16-bit \code{signed int} datatype. Usually an alias
for \var{c_short}.
\end{classdesc}
\begin{classdesc}{c_int32}{\optional{value}}
Represents a C 32-bit \code{signed int} datatype. Usually an alias
for \code{c_int}.
\end{classdesc}
\begin{classdesc}{c_int64}{\optional{value}}
Represents a C 64-bit \code{signed int} datatype. Usually an alias
for \code{c_longlong}.
\end{classdesc}
\begin{classdesc}{c_int8}{\optional{value}}
Represents a C 8-bit \code{signed int} datatype. Usually an alias for \code{c_byte}.
\end{classdesc}
\begin{classdesc}{c_long}{\optional{value}}
Represents a C \code{signed long} datatype. The constructor accepts
an optional integer initializer; no overflow checking is done.
\end{classdesc}
\begin{classdesc}{c_longlong}{\optional{value}}
Represents a C \code{signed long long} datatype. The constructor
accepts an optional integer initializer; no overflow checking is done.
\end{classdesc}
\begin{classdesc}{c_short}{\optional{value}}
Represents a C \code{signed short} datatype. The constructor accepts
an optional integer initializer; no overflow checking is done.
\end{classdesc}
\begin{classdesc}{c_size_t}{\optional{value}}
Represents a C \code{size_t} datatype.
\end{classdesc}
\begin{classdesc}{c_ubyte}{\optional{value}}
Represents a C \code{unsigned char} datatype, and interprets the value
as small integer. The constructor accepts an optional integer
initializer; no overflow checking is done.
\end{classdesc}
\begin{classdesc}{c_uint}{\optional{value}}
Represents a C \code{unsigned int} datatype. The constructor accepts
an optional integer initializer; no overflow checking is done. On
platforms where \code{sizeof(int) == sizeof(long)} \var{c_int} is an
alias to \var{c_long}.
\end{classdesc}
\begin{classdesc}{c_uint16}{\optional{value}}
Represents a C 16-bit \code{unsigned int} datatype. Usually an alias
for \code{c_ushort}.
\end{classdesc}
\begin{classdesc}{c_uint32}{\optional{value}}
Represents a C 32-bit \code{unsigned int} datatype. Usually an alias
for \code{c_uint}.
\end{classdesc}
\begin{classdesc}{c_uint64}{\optional{value}}
Represents a C 64-bit \code{unsigned int} datatype. Usually an alias
for \code{c_ulonglong}.
\end{classdesc}
\begin{classdesc}{c_uint8}{\optional{value}}
Represents a C 8-bit \code{unsigned int} datatype. Usually an alias
for \code{c_ubyte}.
\end{classdesc}
\begin{classdesc}{c_ulong}{\optional{value}}
Represents a C \code{unsigned long} datatype. The constructor accepts
an optional integer initializer; no overflow checking is done.
\end{classdesc}
\begin{classdesc}{c_ulonglong}{\optional{value}}
Represents a C \code{unsigned long long} datatype. The constructor
accepts an optional integer initializer; no overflow checking is done.
\end{classdesc}
\begin{classdesc}{c_ushort}{\optional{value}}
Represents a C \code{unsigned short} datatype. The constructor accepts
an optional integer initializer; no overflow checking is done.
\end{classdesc}
\begin{classdesc}{c_void_p}{\optional{value}}
Represents a C \code{void *} type. The value is represented as
integer. The constructor accepts an optional integer initializer.
\end{classdesc}
\begin{classdesc}{c_wchar}{\optional{value}}
Represents a C \code{wchar_t} datatype, and interprets the value as a
single character unicode string. The constructor accepts an optional
string initializer, the length of the string must be exactly one
character.
\end{classdesc}
\begin{classdesc}{c_wchar_p}{\optional{value}}
Represents a C \code{wchar_t *} datatype, which must be a pointer to a
zero-terminated wide character string. The constructor accepts an
integer address, or a string.
% XXX Explain the difference to POINTER(c_wchar)
\end{classdesc}
\begin{classdesc}{HRESULT}{}
Windows only: Represents a \code{HRESULT} value, which contains
success or error information for a function or method call.
\end{classdesc}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% structured data types
\subsubsection{structured data types}
\begin{classdesc}{BigEndianStructure}{}
\end{classdesc}
\begin{classdesc}{LittleEndianStructure}{}
\end{classdesc}
\begin{classdesc}{Structure}{}
Base class for Structure data types.
\end{classdesc}
\begin{classdesc}{Union}{}
\end{classdesc}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% libraries
\subsubsection{libraries}
\begin{classdesc}{CDLL}{name, mode=RTLD_LOCAL, handle=None}
\end{classdesc}
\begin{datadesc}{cdll}
\end{datadesc}
\begin{classdesc}{LibraryLoader}{dlltype}
\begin{memberdesc}{LoadLibrary}{name, mode=RTLD_LOCAL, handle=None}
\end{memberdesc}
\end{classdesc}
\begin{classdesc}{OleDLL}{name, mode=RTLD_LOCAL, handle=None}
\end{classdesc}
\begin{datadesc}{oledll}
\end{datadesc}
\begin{classdesc}{py_object}{}
\end{classdesc}
\begin{classdesc}{PyDLL}{name, mode=RTLD_LOCAL, handle=None}
\end{classdesc}
\begin{datadesc}{pydll}{}
\end{datadesc}
\begin{datadesc}{RTLD_GLOBAL}
\end{datadesc}
\begin{datadesc}{RTLD_LOCAL}
\end{datadesc}
\begin{classdesc}{WinDLL}{name, mode=RTLD_LOCAL, handle=None}
\end{classdesc}
\begin{datadesc}{windll}
\end{datadesc}
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