Expert Python Programming - Third Edition

Loading libraries

There are exactly four types of dynamic library loaders available in ctypes and two conventions to use them. The classes that represent dynamic and shared libraries are ctypes.CDLL, ctypes.PyDLL, ctypes.OleDLL, and ctypes.WinDLL. The last two are available only on Windows, so we won't discuss them here in detail. The differences between CDLL and PyDLL are as follows:

• ctypes.CDLL: This class represents loaded shared libraries. The functions in these libraries use the standard calling convention and are assumed to return int. GIL is released during the call.
• ctypes.PyDLL: This class works like CDLL, but GIL is not released during the call. After execution, the Python error flag is checked and an exception is raised if it ...