Guido van Rossum wrote:
> > Right. OTOH there seems to be the fear (especially from the
> > more experienced folks maintaining large code bases) that
> > the ternary op *will* be used in non-assignments despite often
> > beeing bad style. E.g. starting from
> >
> > if obj.method():
> > ...
> >
> > and realizing that 'obj' might not have "method" some might write:
> >
> > if obj.method() if hasattr(obj, 'method') else False:
> > ...
> >
> > which many consider a bad thing to be valid. There are a *lot*
> > of variations on this theme (with while/list-comps/lambda) and
> > people have reacted with punctuation (?:), new keywords (when)
> > and any mixture between those. Clearly, you don't need the
> > ternary operator for the above because there is an obvious
> > other solution:
> >
> > if hasattr(obj, 'method') and obj.method():
> > ...
> >
> > and thus people indicated in various threads that having the ternary op
> > prevents people from getting to better and easier solutions.
>
> I'm sorry, but I am not at all swayed by the argument that this can be
> misused. That argument has been used against every new proposal since
> Python 1.0. But the existing constructs can be misused just as well.
> You can't prevent a poor programmer from writing poor code.
Sure, any construct can be abused. Still there are gradual differences.
For example, introducing a new statement usually isn't as harmful
to readability as new forms of expressions can be. The latter can
be used almost eveywhere.
> The example you give is particularly unlikely because the 'and' idiom
> is well established for this particular case.
If somebody knows the right idiom then he will use it, sure. But
somebody learning the ternary-op ("oh i know that from C, cool")
might not even get to the point of knowing about python's special
and/or behaviour ("Oh i know boolean operations from C, right").
The ternary op then becomes the "obvious way to do it". Thus
i am afraid that
if obj.method() if hasattr(obj, 'method') else False:
is not that unlikely for a C-programmer learning Python in 2004
(in a dimension where PEP308 is effective).
regards,
holger
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