[Python-3000] Exception Expressions

[Jim Jewett]

On 8/31/06, Brett Cannon <brett at python.org> wrote:
> On 8/31/06, Calvin Spealman <ironfroggy at gmail.com> wrote:
> > On 8/31/06, Brett Cannon <brett at python.org> wrote:
> > > So this feels like the Perl idiom of using die: ``open(file) or die``

> > "Ouch" on the associated my idea with perl!

> =)  The truth hurts.

Isn't this almost the opposite of "or die"?  Unless I'm having a very
bad day, the die idiom is more like a SystemExit, but this proposal is
a way to recover from expected Exceptions.

    > func(ags) || die(msg)

means

    >>> if not func(args):
    ...     raise SystemExit(msg)

This proposal, with the "a non-dict mapping might not have get"  use case:

    >>> ((mymap[k] except KeyError then default) for key in source)

means

    >>> def __temp():
    ...     for element in source:
    ...         try:
    ...             v=mymap[k]
    ...         except KeyError:
    ...             v=default
    ...         yield v
    >>> __temp()

-jJ