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To: python-list@python.org
From: Rob Williscroft <rtw@rtw.me.uk>
Subject: Re: Returning a value from exec or a better solution
Date: Tue, 30 Aug 2011 07:28:41 +0000 (UTC)
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Xref: x330-a1.tempe.blueboxinc.net comp.lang.python:12429

Jack Trades wrote in
news:CAG5udOh1+oE4g9Frjp3pucbHUtWcN34KK35a-Xs2YqkZH9X5=w@mail.gmail.com
in gmane.comp.python.general: 

>> def test():
>>  src = (
>>       "def double(x):"
>>      "  return x * 2"
>>     )
>>  globals  = {}
>>  exec( src, globals )
>>  return globals[ "double" ]
>>
>> print( test() )
>>
> 
> I looked into doing it that way but it still requires that the user
> use a specific name for the function they are defining.  The docs on
> exec say that an implementation may populate globals or locals with
> whatever they want so that also rules out doing a simple "for item in
> globals", as there may be more than just the one function in there
> (though I suppose I may be able to work around that).
> 
> 

Why not just get the name from the user, or use a regular expression
to extract the first (or last, maybe) definition from the source string.

Rob.