On 6/15/05, Mark Jason Dominus <[EMAIL PROTECTED]> wrote:
>
> > The attached patch rephrases three pieces of Perl documentation which
> > suggest that calling UNIVERSAL::isa() or UNIVERSAL::can() directly is a
> > good idea. The revised version explains why it's a bad idea and gives
> > more correct recommendations.
>
> You seem to have removed all mentions of use of UNIVERSAL::isa($x,
> 'HASH') without either introducing any equivalent replacement or
> indicating any valid reason why it would be a bad idea.
>
> This use of UNIVERSAL::isa is essentially orthogonal to the other
> uses; I think it makes sense to leave it in and document it separately.
Chromatic parenthetically mentioned the replacement for this usage
didn't he? I would have thought that Scalar::Util::reftype() is the
prefered way to do this. (1)
Using UNIVERSAL::isa() is IMO bad as its suseptible to
my $obj=bless [],'HASH';
type nonsense. Having said that, neither reftype() nor
UNIVERSAL::isa() suffice when you consider that most times what you
want to know is whether the object is capable of being dereferenced as
a hash. To do that properly you need to use overload::Overloaded() in
combination with one of the other methods.
Maybe this subject deserves a bigger discussion in the docs?
yves
(1) IMO its a bummer that reftype returns undef for non references as
if it were Pl_sv_no you could say
if (reftype($foo) eq 'HASH') { ... }
without dealing with warnings. As it is you have to say
if (ref $foo and reftype($foo) eq 'HASH') { ... }
which is a bit annoying.
--
perl -Mre=debug -e "/just|another|perl|hacker/"
