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(Roy S. Rapoport) wrote in message news:<. com>...
Ok it took me a while, and I'm not quite sure, but I think I got it:
....
....
....

> However, lets look at the package approach:
> onec.py and twoc.py remain the same. master.py looks slightly
> different:
> class master:
> def dosomething(self, what):
>
> x = __import__("demo."+what)

When what='onec' then after the above statement x will become the **demo**
- package with the possibility to access demo.onec.

> y = eval("x.%s()" % what)

So the above eval-statement tries to call demo.onec(), which results in
your error below.
Instead of this you should try:
**y = eval("x.%s.%s()" % (what,what) )**

> eval("y.dosomething()")

BTW at my opinion there's no need for the eval-statement.
**y.dosomething()** works too.

>
>
> (so the only difference is in that import statement).
>
> Running the test code:
> import demo.master
> F = demo.master.master()
> F.dosomething('one')
>
> Gets me
> ---
> Traceback (most recent call last):
> File "./f2", line 6, in ?
> F.dosomething('one')
> File "./demo/master.py", line 5, in dosomething
> y = eval("x.%s()" % what)
> File "<string>", line 0, in ?
> TypeError: 'module' object is not callable
> ---
>
> So there's some intricacy in dealing with packages I'm not getting;
> unfortunately, the only place I've seen packages documented is the
> tutorial which is, understandably, a little sparse.
>
> -roy

I added some prints in your master-class to clearify a little bit
the situation.
class master:
def dosomething(self, what):
x = __import__("demo."+what)
print "="*30
print "x : %s"%x
print "x.__name__: %s"%x.__name__
print "dir(x) :"
print "\n".join(dir(x))
mod="x.%s.%s()" % (what,what)
print "mod : %s"%mod
y = eval(mod)
y.dosomething()
print "="*30
print

Gives me the following:
==============================
x : <module 'demo' from 'C:\Dokumen ...[snip]
x.__name__: demo
dir(x) :
__all__
__builtins__
__doc__
__file__
__name__
__path__
master
onec
mod : x.onec.onec()
class one called to do something
==============================

==============================
x : <module 'demo' from 'C:\Dokumen ...[snip]
x.__name__: demo
dir(x) :
__all__
__builtins__
__doc__
__file__
__name__
__path__
master
onec
twoc
mod : x.twoc.twoc()
class two called to do something
==============================

Reading http://www.python.org/doc/essays/packages.html could
help a bit.

Regards
Peter

p- (Peter Abel) wrote in message news:< om>...

> > y = eval("x.%s()" % what)
>
> So the above eval-statement tries to call demo.onec(), which results in
> your error below.
> Instead of this you should try:
> **y = eval("x.%s.%s()" % (what,what) )**

Alrighty, then. Now we're cooking with gas, and this does in fact
work.
I'm not sure I have a very strong understanding yet of why it works
(whereas the original didn't), but I'm hoping this:
> Reading http://www.python.org/doc/essays/packages.html could

will in fact clarify things.

Thanks!

-roy