this seems to disagree with the statement of "Memoryview currently only knows the types from the struct module."

why is memoryview aware of _pack_, a implementation detail of ctypes structures. is memoryview a collection of implementation for different types or a unique type on its own?


>>> import ctypes
>>> class B1(ctypes.Structure):
...     _fields_ = [( "data", c_uint8 * 256 ), ]
...     _pack_ = 1
...
>>> class B2(ctypes.Structure):
...     _fields_ = [( "data", c_uint8 * 256 ), ]
...
>>>
>>> a = B1()
>>> b = B2()
>>> memoryview( a ).cast( 'B' )
<memory at 0x01FFCDC0>
>>> memoryview( b ).cast( 'B' )
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ValueError: memoryview: source format must be a native single character format prefixed with an optional '@'
>>>