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Question: Dynamic code import

Károly Ladvánszky aa at bb.cc
Thu Oct 25 16:04:47 EDT 2001 
> Yes, it does. So where is problem?

What I would like to do is import f11 from a file etc.., it is not written
in the script.
Is it possible and how?

"Petr Kubanek" <petr at kubanek.net> az alábbiakat írta a következo üzenetben:
news:9r9q9l$u5i$06$1 at news.t-online.com...
> > For instance, the running program refers to function f1 through ff:
> >
> > def f1(a):
> >     return a*1.25
> >
> > ff=f1
> >
> > At some point, it turns out that f1(a) should return a*1.3+5. If it was
> > possible to insert a
> > new function, the running program could be modified like this:
> >
> > #--- this is to be 'imported'
> > def f11(a):
> >     return a*1.3+5
> > #---
> >
> > ff=f11
> >
> > Now ff(a) would produce results by using the new rule embodied in f11!
>
> Yes, it does. So where is problem?
>
> > 2. Something is wrong with globals. Given the example below, I'd expect
2
> > for the second print.
> >
> > global gx
> > gx=1
> >
> > def set_gx(gx_new):
> >     gx=gx_new
>
> gx is local variable (at that point). Python works so. To work as
expected,
> you should add global:
>
> def set_gx(gx_new):
>     global gx
>     gx=gx_new
>
> >
> > #--- This one works, test() prints the global gx.
> > global gx
> > gx=1
> >
> > def test():
> >     print gx # prints 1
> >
> > b.
> > #--- This one runs to error -> 'UnboundLocalError: local variable 'gx'
> > referenced before assignment' !!!
> > global gx
> > gx=1
> >
> > def test():
> >     print gx
> >     gx=2
>
> Ansewer is in error. Same problem:
>
> def test():
>     global gx
>     print gx
>     gx=2
>
> >
> > c.
> > #--- This one works but treats gx as local. Try test() first, then
test1()
> > will print the original 1 for the global gx!
> > global gx
> > gx=1
> >
> > def test():
> >     gx=2
> >     print gx # prints 2
> >
> > def test1():
> >     print gx # prints 1!
>
> Again, it's in syntax. Insert global gx before first statement in def.
>
> Using global in Python is quite strange and you should try to avoid it, or
> remeber to use global every time. Other possible way is throught __main__
> module, which worked like:
>
> import __main__
>
> __main__.gx=1
>
> def test:
>         print __main__.gx
>
> Even when __main__ gets reimported in second module, it's contents
remains.
>
> Petr Kubanek


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