Example showing that ctypes might be tricky... (the bytes buffer gets garbage collected so we get weird results)

fancy_ctypes.py

In [8]: import ctypes
   ...: 
   ...: 
   ...: class Foo(ctypes.LittleEndianStructure):
   ...:     _fields_ = (('bar', ctypes.c_uint64),)
   ...: 
   ...:     def __str__(self):
   ...:         return 'Foo .bar={}'.format(self.bar)
   ...: 
   ...:     @classmethod
   ...:     def from_bytearray(cls, buf):
   ...:         assert len(buf) == ctypes.sizeof(cls), 'Bytearray and structure size mismatch'
   ...:         return ctypes.cast(bytes(buf), ctypes.POINTER(cls)).contents
   ...: 
   ...: 
   ...: f = Foo.from_bytearray(bytearray(8))
   ...: print(f)
   ...: 
   ...: print(Foo.from_bytearray(bytearray(8)))
   ...: 
   ...: 
   ...: 
Foo .bar=21474836480
Foo .bar=0