[Tutor] how to create a generic instance of an object?

[Danny Yoo]

> Perhaps I'm taking the wrong approach here with the Asset/AssetType
> base-class/sub-class organization; it's beginning to feel that way.
>
> I've tried something like this:
>
> <asset.py>
> class Asset: pass
>
> <foo.py>
> class Foo(Asset): pass
>
> <script.py>
> from asset import Asset
> from foo import Foo
>
> klass = 'Foo'
> o = klass()
>
> which gets me 'string not callable', which is kind of expected.


Hi John,

It sounds like you're trying to do some kind of dynamic linking.  Python
has a builtin called "__import__" that can help: it allows us to do module
import, given an arbitrary name.

Your example above might be written as:

#####################################################################
<asset.py>
class Asset: pass

<foo.py>
class Foo(Asset): pass

<script.py>

def dynamic_lookup(module_name, class_name):
    module_object = __import__(module_name)
    class_object = getattr(module_object, class_name)
    return class_object

klass = dynamic_lookup('foo', 'Foo')
o = klass()
#####################################################################

This can be easily abused.  *grin* But for what you're trying, it might be
what you're looking for.  For more information on __import__, see:

    http://www.python.org/doc/lib/built-in-funcs.html


Hope this helps!