Check class instance passed to another module is of type class-CodePudding

How to check type of class instance object passed from another module. Does it require from main import MyClass? Or can I just generally check object is of type "(any) class instance"?

# main.py
#########

import sub

class MyClass():
    def __init__(self):
        self.z = 1

a = MyClass()
assert type(a) == MyClass
assert isinstance(a, MyClass) == True

b = sub.fun(a)



# sub.py
########

def fun(i):
    if isinstance(i, class):  # general instead of __main__.MyClass
        return i.__dict__

The above yields

NameError: name 'class' is not defined

Maybe it is not a good design and code shall be explicit rather than converting each class to dict?

CodePudding user response：

I want to convert each class instance passed to fun to dictionary

Try the below

class Foo:
    def __init__(self, x):
        self.x = x


class Bar:
    def __init__(self, x):
        self.x = x


def fun(instance):
    if hasattr(instance, '__dict__'):
        return instance.__dict__


print(fun(Foo(56)))
print(fun(Bar("56")))

output

{'x': 56}
{'x': '56'}

CodePudding user response：

Yes, python needs to know which class you are checking because you can have two different classes with the same name in different files.

In file sub.py you have to write:

from main import MyClass

def fun(i):
    if isinstance(i, MyClass): 
        return i.__dict__

But in case you importing fun into main.py you will get circular import, be careful)

CodePudding user response：

# sub.py
########

def fun(i):
    if isinstance(i, class): # <---- class is keyword in Python, you cannot use it 
                             #       like this. You can use as type(class)
        return i.__dict__