changing local namespace of a function

[Bo Peng]

Michael Spencer wrote:

> As you no doubt have discovered from the docs and this group, that isn't 
> doable with CPython.

Too bad to know this.

>  >>> a = {'x':1, 'y':2}
>  >>> b = {'x':3, 'y':3}
>  ...
>  >>> def funa(x,y, **kw):
>  ...     del kw     #Careful of unwanted names in locals with this approach
>  ...     z = x + y
>  ...     return locals()

There are hundreds of items in the dictionary (that will be needed in 
the calculation) so passing the whole dictionary is a lot better than 
passing individual items.

> Alternatively, you could use exec:

Yes. I thought of using exec or eval. If there are a dozen statements,

def fun(d):
   exec 'z = x + y' in globals(), d

seems to be more readable than

def fun(d):
   d['z'] = d['x'] + d['y']

But how severe will the performance penalty be?

Bo