Question

I’m trying to do an __init__.py that load module and instantiate dinamically internal namesake class. With a file tree like

 importer/
     __init__.py         # The file i'm writing
     asd.py              # It contains class asd
     bsd.py              # It contains class bsd

And __init__.py with

importername=__name__

def load(modname,paramlist = []):

  if modname in globals():
    print 'Module %s already loaded.' % (modname)
  else:
    imported_mod = __import__(importername + '.' + modname, fromlist = ["*"])
    try:
        globals()[modname]=getattr(imported_mod,modname)(*paramlist)
    except Exception, e:
        print 'Module %s not loaded: %s.' % (modname, e)

If I run

import importer
importer.load('asd')
print importer.asd.name
'ASD!'

It works like a charm, but if I run

from importer import *
load('asd')
print asd.name
Traceback (most recent call last):
  File "<string>", line 1, in <module>
NameError: name 'asd' is not defined

Can I fix it in some way? Thank you.

Answer 1

There is no such thing as truly global in Python. When you use globals() in importer/__init__.py, you are accessing the module’s namespace. Your second non-working sample is adding ‘asd’ to importer, not to your test module.

The best you could is modify importer so you could do:

from importer import *
asd = load('asd')
print asd.name

But as Thomas K suggests: this is kind of odd, perhaps there’s a simpler way to solve your problem?