On Friday 09 July 2004 19:25, Gunnar Hjalmarsson wrote:
> Philipp Traeder wrote:
> > I don't know what an expert would say,
>
> Neither do I. :)
I think this is a good base for talking about hashes. ;-)
> > but for testing if a hash contains an element, I normally use
> > "exists":
>
> Your wording "if a hash contains an element" is ambigous IMO. A hash
> or associative array consists of key/value pairs, where the keys are
> indexes and the values are considered to be the elements (I think).
Ok - that's a possible terminology, and yes, I wasn't completely precise ;-)
>
> > if (exists ($hash{'mykey'})) {
> > print 'mykey exists.';
> > }
>
> That's fine, as long as you are aware that $hash{mykey} may well be
> undefined even if it "exists".
I think *this* is the interesting point here - it's quite possible that a
certain key exists in a hash, but has an undefined value:
my %hash = (42 => undef);
print "42 exists\n" if (exists $hash{42});
print "42 is defined\n" if (defined $hash{42});
If you ask me, you can't put up a general rule about using "exists" or
"defined" - it's a questions of how/on which conditions the hash has been
filled...
Just my 5 cent,
Philipp
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