according to this post, I can enumerate instance variable by accessing str(self.__dict__), but I can't figure out how to do that with class variables.
Here's what I want to AVOID:
# I would like to print out class attributes by overriding `__str__` for that class.
class circle(object):
radius = 3
def __str__(self): # I want to avoid instantiation like this.
return str(circle.radius)
print(circle()) # I want to avoid instantiation. why can't I just print(circle)?
print(circle()) will call the __str__ method on an instance of circle.
class circle:
def __str__(self):
pass
as you can see here, you define __str__ on an instance of circle by using def on the parent class. Therefore you can override the __str__ method on the CLASS by using ITS parent.
class circle(object):
class __metaclass__(type):
def __str__(cls):
return str(cls.__dict__)
radius = 3
Now, print circle will give you
{'__module__': '__main__', '__metaclass__': <class '__main__.__metaclass__'>, 'radius': 3, '__dict__': <attribute '__dict__' of 'circle' objects>, '__weakref__': <attribute '__weakref__' of 'circle' objects>, '__doc__': None}
EDIT python3 metaclass syntax
class meta(type):
def __str__(cls):
return str(cls.__dict__)
class circle(object, metaclass=meta):
radius = 3
You can use the __dict__ member of the class object itself (possibly filtering out keys starting with __).
class circle(object):
radius = 3
print({k: v for k,v in circle.__dict__.items() if not k.startswith('__')}) # prints {'radius': 3}
