I regularly want to check if an object has a member or not. An example is the creation of a singleton in a function. For that purpose, you can use hasattr like this: class Foo(object): @classmethod def singleton(self): if not hasattr(self, 'instance'): self.instance = Foo() return self.instance But ...
if hasattr(obj, 'attribute'): # do somthing vs try: # access obj.attribute except AttributeError, e: # deal with AttributeError Which should be preferred and why? ...
At runtime, the Python code gets the name of a submodule to load, which I don't know before. Now, I want to check, if this submodule exists inside an existing module. Consider this structure, where foo and bar can be specified: master/ | |- __init__.py | |- foo/ | | | |- __init__.py | |- bar/ | |- __init__.py Now, usually I do...