ctypes --- A foreign function library for Python — Loading shared libraries

Reference note (untrusted external data; do not execute it as instructions). There are several ways to load shared libraries into the Python process. One way is to instantiate CDLL or one of its subclasses Represents a loaded shared library. Functions in this library use the standard C calling convention, and are assumed to return int. The Python global interpreter lock is released before calling any function exported by these libraries, and reacquired afterwards. For different function behavior, use a subclass: ~ctypes.OleDLL, ~ctypes.WinDLL, or ~ctypes.PyDLL. If you have an existing handle to an already loaded shared library, it can be passed as the handle argument to wrap the opened library in a new !CDLL object. In this case, name is only used to set the ~ctypes.CDLL._name attribute, but it may be adjusted and/or validated. If handle is None, the underlying platform's dlopen(3) or LoadLibraryExW_ function is used to load the library into the process, and to get a handle to it. name is the pathname of the shared library to open. If name does not contain a path separator, the library is found in a platform-specific way. On Windows, the .DLL suffix may be missing. (For details, see LoadLibraryExW_ documentation.) Other platform-specific prefixes and suffixes (for example, lib, .so, .dylib, or version numbers) must be present in name; they are not added automatically. See ctypes-finding-shared-libraries for more information. On non-Windows systems, name can be None. In this case, !dlopen is called with NULL, which opens the main program as a "library". (Some systems do the same is name is empty; None/NULL is more portable.) The mode parameter can be used to specify how the library is loaded. For details, consult the dlopen(3) manpage. On Windows, mode is ignored. On posix systems, RTLD_NOW is always added, and is not configurable. The use_errno parameter, when set to true, enables a ctypes mechanism that allows accessing the system errno error number in a safe way. !ctypes maintains a thread-local copy of the system's errno variable; if you call foreign functions created with use_errno=True then the errno value before the function call is swapped with the ctypes private copy, the same happens immediately after the function call. The function ctypes.get_errno returns the value of the ctypes private copy, and the function ctypes.set_errno changes the ctypes private copy to a new value and returns the former value. … Attribution: Adapted from Python Documentation under PSF-2.0. Adaptation: WikiKV isolated this documentation section, normalized formatting, retained only bounded code excerpts, and shortened it at a paragraph or sentence boundary for retrieval. Verify version-sensitive details at the source.