Python3 exec locals - this must be a FAQ

Dave Angel davea at
Tue Feb 12 14:27:41 CET 2013

On 02/12/2013 06:46 AM, Helmut Jarausch wrote:
> Hi,
> I've tried but didn't find an answer on the net.
> The exec function in Python modifies a copy of locals() only.
> How can I transfer changes in that local copy to the locals of my function
> ** without **  knowing the names of these variables.
> E.g.  I have a lot of local names.
> Doing
> _locals= locals()

This doesn't copy everything.  But perhaps you know that and you're just 
testing us.

> expr=compile(input('statements assigning to some local variables '),
>                                                   'user input','exec')
> exec(expr,globals(),_locals)
> How can I "copy" the new values within _locals to my current locals.
> If I knew that  Var1  has changed I could say
> Var1 = _locals['Var1'] but what to do in general?

locals()["Var1"] = _locals["Var1"]  will set the same Var1 local.

So you might write a loop on _locals.

But beware if someone has deleted one of the "variables" it may not do 
what you'd like.  You cannot necessarily add back a local with the above 


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