How to find out in which module an instance of a class is created?
Johannes Janssen
I like to know in which module an instance of a class was initialized.
Using __module__ or __name__ within a class only gives me the module in
which the class was defined not the instance of the class. Is there some
(simple) way to do this?
For better understanding I'll give an example how I want to use this.
Okay let's say I've got a module *foo,* in which class A is defined as
the following:
> class A(object):
> def __init__(self, mod):
> self.mod = mod
In a module called *bar* I do the following:
> import foo
> a = A(__name__)
Then a.mod should be "bar". But I don't like to pass the value of a.mod
manually rather than having it default to the module the instance a of A
was created in (here "bar").
Unfortunately something like this ...
> class A(object):
> def __init__(self, mod=__name__):
> self.mod = mod
... won't work. In this case mod would always be "foo".
Kind regards
johannes
Christian Heimes
> > class A(object):
> > def __init__(self, mod=__name__):
> > self.mod = mod
>
You have to inspect the stack in order to get the module of the caller.
The implementation of warnings.warn() gives you some examples how to get
the module name.
Christian
Johannes Janssen
warnings.warn(), I came up with this:
import sys
class A(object):
def __init__(self, mod=None):
if mod is None:
self.mod = sys._getframe(1).f_globals['__name__']
else:
self.mod = mod
In warnings.warn() they used try around sys._getframe(1). As far as I
understand what is done in warnings, there it is not sure what object
caused the warning and therefore it is not sure whether you can or
cannot use sys._getframe(1). Though in my case it should be quite clear.
Can I be sure that my code will always work?
Johannes
Gabriel Genellina
<ma...@johannes-janssen.de> escribiￜ:
> class A(object):
> def __init__(self, mod=None):
> if mod is None:
> self.mod = sys._getframe(1).f_globals['__name__']
> else:
> self.mod = mod
>
> In warnings.warn() they used try around sys._getframe(1). As far as I
> understand what is done in warnings, there it is not sure what object
> caused the warning and therefore it is not sure whether you can or
> cannot use sys._getframe(1). Though in my case it should be quite clear.
> Can I be sure that my code will always work?
The try/except around sys._getframe(1) is because that function is not
mandatory/available on all Python implementations (that's the case for
jython which doesn't provide it).
--
Gabriel Genellina
Johannes Janssen
> The try/except around sys._getframe(1) is because that function is not
> mandatory/available on all Python implementations (that's the case for
> jython which doesn't provide it).
Thanks, shouldn't such information be part of the python documentation
of sys._getframe()
(http://docs.python.org/library/sys.html?highlight=sys._getframe#sys._getframe)?
Johannes
Chris Rebert
The leading underscore kinda indirectly implies it, but yeah, it's
worth mentioning.
File a bug in the docs: http://bugs.python.org/
Cheers,
Chris
--
http://blog.rebertia.com