[Python-Dev] I'd like list.pop to accept an optional second

[Jim Fulton]

Gordon McMillan wrote:
> 
> Jim Fulton wrote:
> 
> > Gordon McMillan wrote:
> > >
> > > Then how do I get the old behavior?
> >
> > Just pass 0 or 1 argument.
> >
> > >(I've been known to do odd
> > > things - like change behavior based on the number of args - in
> > > extension modules, but this ain't an extension).
> >
> > It *is* a built-in method.  It will be handled just like
> > dictionaries handle the second argument to get.
> 
> d.get(nonexistantkey) does not throw an exception, it returns None.

Oops, I'd forgotten that.

> If list.pop() does not throw an exception when list is empty, it's
> new behavior.
> 
> Which are you asking for:
>  breaking code that expects IndexError

No.

> Violating Pythonic expectations by, in effect, creating 2 methods
>  list.pop(void)
>  list.pop(default_return)

Yes, except that I disagree that this is non-pythonic.

Jim

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