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-   -   access interactive namespace from module (shared namespace?) (http://www.velocityreviews.com/forums/t616754-access-interactive-namespace-from-module-shared-namespace.html)

Ulrich Dorda 05-25-2008 09:47 AM

access interactive namespace from module (shared namespace?)
 
I've got a probably embarrassing trivial problem with namespaces, but couldn't solve it
myself nor find an answer in the net. Hopefully one of you guys can help me.

What I want to do:
Use the interactive shell and e.g define the variable a there.
Then load a module and access a from within.

e.g file "utest.py"

def doit():
print 2*a

in the shell:

import utest
a=3
utest.doit() <- I want this to print 2*a, but of course obtain: <type
exceptions.NameError'>: global name 'a' is not defined

Any change I do to a in the shell should be seen from the doit() function, any variable
assignment I do in the doit() function should be seen in the shell. I guess it's somehow a
namespace sharing.

Actually the function doit() will contain an eval() function that should evaluate a (via a
gui) dynamically inserted expression.

Any one got a clue? (a clue what I try to say and how to help?!)

Thanks a lot in advance!!

Ulrich



TeroV 05-25-2008 10:17 AM

Re: access interactive namespace from module (shared namespace?)
 
Ulrich Dorda wrote:
> I've got a probably embarrassing trivial problem with namespaces, but
> couldn't solve it myself nor find an answer in the net. Hopefully one of
> you guys can help me.
>
> What I want to do:
> Use the interactive shell and e.g define the variable a there.
> Then load a module and access a from within.
>
> e.g file "utest.py"
>
> def doit():
> print 2*a
>
> in the shell:
>
> import utest
> a=3
> utest.doit() <- I want this to print 2*a, but of course obtain: <type
> exceptions.NameError'>: global name 'a' is not defined
>
> Any change I do to a in the shell should be seen from the doit()
> function, any variable assignment I do in the doit() function should be
> seen in the shell. I guess it's somehow a namespace sharing.
>
> Actually the function doit() will contain an eval() function that should
> evaluate a (via a gui) dynamically inserted expression.
>
> Any one got a clue? (a clue what I try to say and how to help?!)
>
> Thanks a lot in advance!!
>
> Ulrich
>
>


Here is one way

#utest.py:
def doit(valuemap):
print 2*valuemap['a']

Python 2.5.1 (r251:54863, Mar 7 2008, 04:10:12)
[GCC 4.1.3 20070929 (prerelease) (Ubuntu 4.1.2-16ubuntu2)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> a = 4
>>> import utest
>>> utest.doit(locals())

8
>>>


ulrich@dorda.net 05-25-2008 10:32 AM

Re: access interactive namespace from module (shared namespace?)
 
Thanks for the reply,

Of course the suggested solution is working and good, but a bit
complicated. The module/function where i need to access the variable
value from the interactive shell is burried quite deep and I would
nedd to hand the locals() quite often from one module to another.
Furthermore it makes the call function slightly more complicated, as
the locals()-argunment has to be given every time.

I was hoping for something a bit different: If I wanted to access a
value b from another module "utest2.py", I would simply need to type
in utest.py: import utest2; print 2*utest2.b
Isn't there a name for the interactive namespace (like here the
utest2), which I can use to access the variable without handing the
whole dictionary?

Cheers,

Ulrich




Peter Otten 05-25-2008 10:38 AM

Re: access interactive namespace from module (shared namespace?)
 
Ulrich Dorda wrote:

> I've got a probably embarrassing trivial problem with namespaces, but
> couldn't solve it myself nor find an answer in the net. Hopefully one of
> you guys can help me.
>
> What I want to do:
> Use the interactive shell and e.g define the variable a there.
> Then load a module and access a from within.
>
> e.g file "utest.py"
>
> def doit():
> print 2*a
>
> in the shell:
>
> import utest
> a=3
> utest.doit() <- I want this to print 2*a, but of course obtain: <type
> exceptions.NameError'>: global name 'a' is not defined
>
> Any change I do to a in the shell should be seen from the doit() function,
> any variable assignment I do in the doit() function should be seen in the
> shell. I guess it's somehow a namespace sharing.
>
> Actually the function doit() will contain an eval() function that should
> evaluate a (via a gui) dynamically inserted expression.
>
> Any one got a clue? (a clue what I try to say and how to help?!)
>
> Thanks a lot in advance!!


While the sane approach to this is

def doit(a):
print 2 * a

here is an insane one:

import sys

def f(): pass
function = type(f)

def snatch_globals(f):
def g(*args, **kw):
return function(f.func_code, sys._getframe(1).f_globals)(*args,
**kw)
return g

@snatch_globals
def doit():
print 2 * a

Peter

ulrich@dorda.net 05-25-2008 12:56 PM

Re: access interactive namespace from module (shared namespace?)
 
Thanks a lot to all!

Apart from obtaining the solution I was searching for, I learned a lot
by studying your answers!

Cheers,

Ulrich


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