Print all fields of ctypes "Structure" with introspection
How about using getattr
?
>>> from ctypes import *
>>>
>>> class S(Structure):
... _fields_ = [
... ('a', c_byte),
... ('b', c_int),
... ('c', c_float),
... ('d', c_double)
... ]
...
>>> s = S(1, 2, 3, 4.0)
>>>
>>> for field_name, field_type in s._fields_:
... print field_name, getattr(s, field_name)
...
a 1
b 2
c 3.0
d 4.0
UPDATE
If there is a bitfield in the structure (or union), iterating _fields_
yield a tuple of 3 items which will cause ValueError
. To prevent that you need to adjust the code:
...
for field in s._fields_:
print field[0], getattr(s, field[0])
I've just come up with this, for a project I'm working on that has several C structures I want to be able to pretty-print (in a Jupyter notebook, in my case):
>>> # https://stackoverflow.com/a/62011887/76452
>>>
>>> from ctypes import Structure, c_byte, c_int, c_float, c_double
>>>
>>>
>>> class MyStructure(Structure):
...
... def __repr__(self) -> str:
... values = ", ".join(f"{name}={value}"
... for name, value in self._asdict().items())
... return f"<{self.__class__.__name__}: {values}>"
>>>
>>> def _asdict(self) -> dict:
... return {field[0]: getattr(self, field[0])
... for field in self._fields_}
>>>
>>>
>>> class S(MyStructure):
... _fields_ = (
... ('a', c_byte),
... ('b', c_int),
... ('c', c_float),
... ('d', c_double)
... )
>>>
>>> s = S(1, 2, 3.0, 4.0)
>>> s
<S: a=1, b=2, c=3.0, d=4.0>