i am trying to create an instance of a class using arguments, and the problem is my meta class needs some positional args to decide about the bases of class creation.
here is an example to clear it more:
import inspect
import sys
class ParentA:
pass
class Child1(ParentA):
def ch1_cmd(self):
print('This is RAM Telnet IOS Cisco ')
class Child2(ParentA):
def ch2_cmd(self):
print('This is Time Telnet IOS Cisco ')
Here is my metaclass which accepts an additional argument CONNECTION_TYPE which is a dictionary, so metaclass will load proper childs according to this Dictionary
class MainMeta(type):
def __new__(cls, clsname, bases, clsdict, CONNECTION_TYPE):
if CONNECTION_TYPE != None:
CONNECTION_TYPE['OBJ'] = getattr(
sys.modules[__name__], CONNECTION_TYPE['OBJ'])
if CONNECTION_TYPE['TYPE'] == 'CONDITION1':
if CONNECTION_TYPE['CONNECTION_TYPE'] == 'CONDITION2':
bases = []
for name, obj in inspect.getmembers(sys.modules[__name__]):
if inspect.isclass(obj):
if CONNECTION_TYPE['OBJ'].__subclasscheck__(obj):
if CONNECTION_TYPE['OBJ'].__name__ != obj.__name__:
bases.append(obj)
bases = tuple(bases)
print(clsname, bases, clsdict) # here Shows that bases are loaded CORRECTLY
return super().__new__(cls, clsname, bases, clsdict)
this is the Dictionary which will be served to the meta class.
clsdic = {'TYPE': 'CONDITION1',
'CONNECTION_TYPE': 'CONDITION2', 'OBJ': "ParentA", }
HERE IS The PROBLEM, I use exec to create my class dynamically with my desired CONNECTION_TYPE dictionary, code runs without Err but there are something missing in the created class, and those are __module__
and child classes.
def dev_creator(*args, **kwargs):
print()
myclass = f"""class MyMain(metaclass=MainMeta, CONNECTION_TYPE={kwargs}):\n pass\n"""
return exec(myclass, globals())
dev = dev_creator(**clsdic)
print(dir(dev))
This is the output :|
MyMain (<class '__main__.Child1'>, <class '__main__.Child2'>) {'__module__': '__main__', '__qualname__': 'MyMain'}
['__bool__', '__class__', '__delattr__', '__dir__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__gt__', '__hash__', '__init__', '__init_subclass__', '__le__', '__lt__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__']
HUM, Solved. it was the global variable definition problem.
here is how we should call an exec and get a return from it.
dev = None
def dev_creator(*args, **kwargs):
# print(kwargs)
myclass = f"""class MyMain(metaclass=MainMeta, CONNECTION_TYPE={kwargs}):\n pass\ndev = MyMain"""
exec(myclass, globals(), dev)
return dev