Getting module path string from a class instance

Some Developer someukdeveloper at gmail.com
Tue Nov 13 17:15:13 CET 2012


On 13/11/2012 08:49, Steven D'Aprano wrote:
> On Tue, 13 Nov 2012 07:54:32 +0000, Some Developer wrote:
>
>> On 13/11/2012 07:19, Steven D'Aprano wrote:
>>> On Tue, 13 Nov 2012 06:38:31 +0000, Some Developer wrote:
>>>
>>>> I'm trying to find a way to get a string of the module path of a
>>>> class.
>>>>
>>>> So for instance say I have class Foo and it is in a module called
>>>> my.module. I want to be able to get a string that is equal to this:
>>>> "my.module.Foo". I'm aware of the __repr__ method but it does not do
>>>> what I want it to do in this case.
>>>>
>>>> Can anyone offer any advice at all?
>>> py> from multiprocessing.pool import Pool py> repr(Pool)
>>> "<class 'multiprocessing.pool.Pool'>"
>>>
>>> Seems pretty close to what you ask for. You can either pull that string
>>> apart:
>>>
>>> py> s = repr(Pool)
>>> py> start = s.find("'")
>>> py> end = s.rfind("'")
>>> py> s[start+1:end]
>>> 'multiprocessing.pool.Pool'
>>>
>>> or you can construct it yourself:
>>>
>>> py> Pool.__module__ + '.' + Pool.__name__ 'multiprocessing.pool.Pool'
>>>
>>>
>> Yeah I considered doing it this way but was wary of that method because
>> of possible changes to the implementation of the __repr__ method in the
>> upstream code. If the Django developers don't consider the __repr__
>> method a public API then it could change in the future breaking my code.
> I didn't call SomeClass.__repr__. That is an implementation detail of
> SomeClass, and could change.
>
> I called repr(SomeClass), which calls the *metaclass* __repr__. That is
> less likely to change, although not impossible.
>
>
> If you're worried, just use the second way:
>
> SomeClass.__module__ + '.' + SomeClass.__name__
>   

Ah, my mistake. Thanks. That sounds exactly like what I want.

>> Of course this might not happen but I was hoping that there was a more
>> generic way of doing it that did not rely on a certain implementation
>> being in existence.
> SomeClass.__name__ is the official way to get the name of a class;
> SomeClass.__module__ is the official way to get the name of the module or
> package it comes from.


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