If you pass an object which supports the buffer protocol to struct.unpack it will fail because it specifically checks for a string. You should use PyObject_AsReadBuffer instead. If this code is performance critical, you could add an unpack_buffer method or something like that.
Logged In: YES user_id=1067739 Well, because it broke previously working code and there is no warning in the documentation about that. In the mean-time, I've found out about pack_into and unpack_from which accept buffer like objects. Note that they are not documented in the struct module section, only mentioned in the "What's new" chapter.
Logged In: YES user_id=1067739 The actual code which broke used a Pointer extension class implemented in C++. I reproduced the problem using array.array. Using array in this way (without calling tostring) looks a bit weird.
