how to create a python object where every attribute is None-CodePudding

I'm not sure if this can be done, but I would like an object where you can query any attribute, and it just returns None, instead of an error.

eg.

>>> print(MyObject.whatever)
None
>>> print(MyObject.abc)
None
>>> print(MyObject.thisisarandomphrase)
None

without manually assigning all of these values in the object's __init__ function

CodePudding user response：

You can define __getattribute__:

class MyObject:
    def __getattribute__(self, name):
        return None  # or simply return
    
x = MyObject()
print(x.abc)
print(x.xyz)

output:

None
None

NB. note that is might not work with all attributes, there are reserved words, e.g. x.class

CodePudding user response：

No sure if I understood your question (not very good at english), but i think you could try using hasattr (https://docs.python.org/3/library/functions.html#hasattr) to check if the attribute exist and return wathever you want if it doesnt

CodePudding user response：

In case you still want the class to return actual attributes when they do exist, you could have __getattribute__ catch attribute errors:

class MyObject(object):
    def __getattribute__(self, name):
        try:
            return object.__getattribute__(self, name)
        except AttributeError:
            return None

CodePudding user response：

I would imagine that if the attribute does actually exist that you'd want its value, therefore I propose:

class MyClass:
    def __init__(self):
        self.a = 1
    def __getattr__(self, name):
        try:
            return super(MyClass, self).__getattr__(name)
        except AttributeError:
            pass
        return None

mc = MyClass()

print(mc.a)
print(mc.b)

Output:

1
None