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Python Discussion Thread
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Jun 15th, 2008

eval() problems

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Hi, I was wondering how to get around a problem I was having with eval(). I have a list of strings and each one is the name of a python file found in the same directory as the current script. I was it to import these modules to use in the current script, but: eval( "import" + modname ), where 'modname' is the script's name, causes an error. Is there any way to have the script import any found scripts or would I have to explicitly add "import <name>" for each script? Thanks!

Python Syntax (Toggle Plain Text)
names = [ "main", "secondary", "tertiary" ]
for item in names:
    eval( "import " + item )
names = [ "main", "secondary", "tertiary" ]
for item in names:
    eval( "import " + item )

The code above makes sense, but python gives me this instead:

Python Syntax (Toggle Plain Text)

import primary
     ^
SyntaxError: invalid syntax

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shadwickman

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Posting Pro in Training

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Jun 16th, 2008

Re: eval() problems

Try ...

python Syntax (Toggle Plain Text)
names = [ "main", "secondary", "tertiary" ]
for item in names:
    cmd = "__import __(%s)" % item 
    eval( cmd )
names = [ "main", "secondary", "tertiary" ]
for item in names:
    cmd = "__import __(%s)" % item 
    eval( cmd )

Last edited by vegaseat; Jun 16th, 2008 at 12:25 am.

vegaseat

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DaniWeb's Hypocrite

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Jun 16th, 2008

Re: eval() problems

I no longer got an error about the import function, but now, however, when I call a function from the "primary" module, it gives me an error saying:
NameError: name 'primary' is not defined.
So when I call function "draw()" from module "primary", it gives me the above error. Any ideas?

shadwickman

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Jun 16th, 2008

Re: eval() problems

Try and see this... I've been trying similar things after I read it and I had some trouble solving my bugs too... I needed the name of a class in a module in a package to be imported ...I still didn't get there but maybe your case is easier

http://technogeek.org/2007/05/29/dyn...g-in-python-2/

tzushky

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Jun 16th, 2008

Re: eval() problems

Besides, that you do not have a "primary" module in the code...
Eval evaluates an expression in his own namespace and returns the result.
What you really want imho is to inject code.

Something like this:

python Syntax (Toggle Plain Text)
for item in names:
    exec "import " + item
for item in names:
    exec "import " + item

slate

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Jun 16th, 2008

Re: eval() problems

Oh awesome - I got it working using exec . I never knew that it existed... Thanks for solving my problem!

shadwickman

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