CODEWITHSUNDEEP
pythonclasspython-2.7
tjati
tjati

Reputation: 6079

Why does setattr does not work as a method?

I want to change some attributes of a class programmtically.

I found, that there's the setattr-function, but it does not work as exptected.

> obj.setattr('bar', 99)
'MyClass' object has no attribute 'setattr'

Instead, I have to use

> setattr(obj, 'bar', 99)

Why is this? I thought, in python the call of a method by an object sets the object itself as the first parameter and so both should mean the same.

Or does Object simply not has the definition of setattr?

Upvotes: 1

Views: 2850

Answers (1)

WKPlus
WKPlus

Reputation: 7255

The object setattr method is __setattr__:

>>> dir(object)
['__class__', '__delattr__', '__doc__', '__format__', '__getattribute__', '__hash__', '__init__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__']

And __setattr__('y', v) will be called when you use x.y = v.

The help info of setattr:

setattr(x, 'y', v) is equivalent to ``x.y = v''.

So setattr(x, 'y', v) is equivalent to x.y = v and then equivalent to x.__setattr__('y', v)

Upvotes: 3

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