ctypes reference

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  Note

    This reference is probably not worth it's name, so incomplete it is.

  Common operations on ctypes instances

    'sizeof(obj) -> integer'

        Return an integer specifying the number of bytes in the memory
        block.  This corresponds to the C code 'sizeof(obj)'.  Does
        also work for types.

    'byref(obj) -> cparam-object'

        Similar to '&obj' in C code, but only usable for passing the
        object as a parameter to a C function call.

    'pointer(obj) -> ctypes instance'

        Same as '&obj' in C.  Different from 'byref(obj)', this
        creates a new ctypes object, acting as a pointer to 'obj'.  It
        will be an instance of a pointer class pointing to 'type(obj)'
        instances.  The pointer class is created on the fly, if it
        does not yet exist.

    'addressof(obj) -> integer'

        Same as '(int)&obj' in C.  Returns the address of the internal
        memory buffer as an integer.


  Common operation on ctypes types

    ctypes types/classes extensively use the new Python type system, so
    the following may first look unusual to the Pyhon programmer.

    'POINTER(ctype) -> class'

        Return a subclass of 'ctype'. Instances of this class are
        pointers to 'ctype'.  The subclass will be created if it does
        not yet exist, otherwise it is returned from a builtin cache.

    'ctype * num -> array class'

        Multiplying a 'ctype' class with a positive integer creates a
        subclass of 'Array'. Instances are arrays holding 'num'
        instances of 'ctype'.

    'ctype.from_address(address) -> ctypes instance'

        Create a new instance of 'ctype' from the memory block at the
        integer 'address'. It must no longer be accessed if the memory
        block becomes invalid, the programmer must ensure this.


  ctypes instance methods/properties

    'obj._as_parameter_ -> magic'

        Automatically called when a ctype object is used as a
        parameter in a C function call *by value*.  Must *return*
        something that can be understood by the C function call
        parameter converter.  Currently, it either returns an integer,
        a string or a unicode string. These are passed as the
        corresponding C data type to the function call.