[Python-Dev] Adding a conditional expression in Py3.0 (original) (raw)

Jack Diederich jack at performancedrivers.com
Tue Sep 20 20:14:23 CEST 2005

On Tue, Sep 20, 2005 at 09:04:53AM -0700, Guido van Rossum wrote:

On 9/20/05, Michael Hudson <mwh at python.net> wrote: > Guido van Rossum <guido at python.org> writes: > > > On 9/19/05, Raymond Hettinger <raymond.hettinger at verizon.net> wrote: > >> I propose that in Py3.0, the "and" and "or" operators be simplified to > >> always return a Boolean value instead of returning the last evaluated > >> argument. > > > > While you're at it, maybe we should switch to && and || as well? > > That's another thing I always mistype when switching between > > languages... > > You're joking, surely?

I wasn't, but I wasn't pushing for it either. Consider it withdrawn given the response. > > Also, this proposal needs to be considered together with the addition > > of a proper conditional operator, like x?y:z. > > I think this discussion has been had before, you know. Unfortunately, if we were to accept Raymond's proposal, we'd have to revisit the discussion, since his proposal removes several ways we currently avoid the need. In fact, I think Raymond's example is more properly considered an argument for adding a conditional expression than for removing the current behavior of the and/or shortcut operators; had we had a conditional expression, he wouldn't have tried to use the "x and y or z" syntax that bit him. Given this realization, I'm now -1 on Raymond's idea, and +1 on adding a conditional expression. I believe (y if x else z) was my favorite last time, wasn't it? I've changed the subject accordingly.

I'm +1 for allowing authors to write return bool(thing or default) when they mean a function to return a bool. I had the "privilege" of working in a large base of perl code (a learning experience) and while some engineers abused functions that were documented as only returning true/false by depending on the side effects of 'and' and 'or' this was easily fixed. The functions were changed to literally return a plain true or false value and those engineers were summarily fired.

I'm a dependable Hettinger fanboy but on this one I have to agree with the we're-all-adults club. Let the authors type an extra few chars if they want to make the code match the intent.

-jackdied

More information about the Python-Dev mailing list