Getting module path string from a class instance

[Some Developer]

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?

 

[Steven D'Aprano]

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'

 

[Some Developer]

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.

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.

 

[Steven D'Aprano]

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__

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.

 

[Some Developer]

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.