`exec`-based routine crashes app upon migration from 3.4.3 to python 3.5.2.
Chris Angelico
rosuav at gmail.com
Thu Jul 28 14:40:53 EDT 2016
On Fri, Jul 29, 2016 at 1:47 AM, Enjoys Math <enjoysmath at gmail.com> wrote:
> I've manually set breakpoints and traced this app crash back to this
> function:
>
> def loadLSobjsOfType(self, objType, listJ):
> if listJ != None:
> for objJ in listJ:
> _locals = locals()
> exec('obj = ' + objType + '(self)', None, _locals)
> obj = _locals['obj']
> obj.loadJson(objJ)
> self.addLSobjOfType(objType, obj)
>
> when breakpoints are set on `obj=_locals['obj']` my wingware debugger kicks
> in and throws a KeyError exeption.
>
> So what's the proper way to get the return value of an exec call when there
> is one?
(Side point: Be aware that it's perfectly legal for a Python
interpreter to make mutations to locals() actually significant. You're
safe here, but just make sure that can't ever bite you.)
By the look of things, you're executing code using a locals but no
globals, and it's executing code at the global scope. Can you simply
remove the 'None' parameter, and thus make _locals be the exec'd
code's locals AND globals both?
Incidentally, what exactly is objType? By the name, I'd suspect that
it's a simple identifier, in which case I would strongly recommend not
using exec at all, but just looking up that name in some dictionary
(maybe globals()??) and calling the result. It'd be a lot simpler and
more efficient.
ChrisA
More information about the Python-list
mailing list