import ctypes
class C_struct:
"""Decorator to convert the given class into a C struct."""
# contains a dict of all known translatable types
types = ctypes.__dict__
@classmethod
def register_type(cls, typename, obj):
"""Adds the new class to the dict of understood types."""
cls.types[typename] = obj
def __call__(self, cls):
"""Converts the given class into a C struct.
Usage:
>>> @C_struct()
... class Account:
... first_name = "c_char_p"
... last_name = "c_char_p"
... balance = "c_float"
...
>>> a = Account()
>>> a
<cstruct.Account object at 0xb7c0ee84>
A very important note: while it *is* possible to
instantiate these classes as follows:
>>> a = Account("Geremy", "Condra", 0.42)
This is strongly discouraged, because there is at
present no way to ensure what order the field names
will be read in.
"""
# build the field mapping (names -> types)
fields = []
for k, v in vars(cls).items():
# don't wrap private variables
if not k.startswith("_"):
# if its a pointer
if v.startswith("*"):
field_type = ctypes.POINTER(self.types[v[1:]])
else:
field_type = self.types[v]
new_field = (k, field_type)
fields.append(new_field)
# make our bases tuple
bases = (ctypes.Structure,) + tuple((base for base in cls.__bases__))
# finish up our wrapping dict
class_attrs = {"_fields_": fields, "__doc__": cls.__doc__}
# now create our class
return type(cls.__name__, bases, class_attrs)
