On 26/05/10 19:48, Mark Dickinson wrote:
This is a long way from my area of expertise (I'm commenting here
because it was me who sent Colin here in the first place), and it's
not clear to me whether this is a bug, and if it is a bug, how it
could be resolved.  What would the impact be of having the compiler
produce 'LOAD_NAME' rather than 'LOAD_GLOBAL' here?

exec with a single argument = module namespace
exec with two arguments = class namespace

Class namespaces are deliberately exempted from lexical scoping so that methods can't see class attributes, hence the example in the tracker issue works exactly as it would if the code was written as a class body.

  class C:
    y = 3
    def execfunc():
      print y
    execfunc()

With this code, y would end up in C.__dict__ rather than the module globals (at least, it would if it wasn't for the exception) and the call to execfunc fails with a NameError when attempting to find y.

I know I've closed other bug reports that were based on the same misunderstanding, and I didn't understand it myself until Guido explained it to me a few years back, so suggestions for improving the exec documentation in this area would be appreciated.

Cheers,
Nick.

--
Nick Coghlan   |   ncogh...@gmail.com   |   Brisbane, Australia
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