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Postings from September 2016
On Tue, Sep 6, 2016 at 4:51 PM, Paul "LeoNerd" Evans <leonerd@leonerd.org.uk
> wrote:
> On Mon, 5 Sep 2016 21:23:54 -0500
> David Nicol <davidnicol@gmail.com> wrote:
>
> > I agree. We already have a way to "ask the lhs whether it matches" and
> > that system is called method dispatch.
> >
> > sub UNIVERSAL::DumbMatch{0}
> > sub DumbMatchOnOdd::DumbMatch{ [0,1]->[$_[1] % 2] }
> > ...
> > $SomeObjectOrOther->DumbMatch($PretzelPattern) and say "got a
> > pretzel";
>
> Well, almost. That is a bit dirty and pollutes the UNIVERSAL namespace.
>
> Nicer would be if perl had notations for "try to call this method but
> if it doesn't exist, yield some sentinel falsey value like undef or
> empty list".
Oh, and yield the same falsey value for a lhs that isn't a blessed
reference, right?
;-)
… okay, I'm sure someone reading this might not be aware that they
already know this, so …
eval { $SomeThing->DumbMatch($PretzelPattern }
(Aside from $SIG{__DIE__}, damn it, the problem with this is if the
string value of $SomeThing is a class name. But that problem was there
ever since the method dispatch hammer was chosen for this particular nail.)
Eirik
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