RE: arrays, hashes unified indexing syntax impact on futurevariat ion s on other collection types [x-bayes]
Piers Cawley wrote:
Garrett Goebel [EMAIL PROTECTED] writes:
What was the reason again which Larry rejected unifying the
syntax for array and hash indexing? As Piers said, we know
whether $a is an array or hash reference when we do:
print $a-{foo};
But as someone else pointed out, there may be classes that have both
hashlike and arraylike interfaces. For instance:
my $queue = SomeQueue.new;
$queue.push('foo');
$queue.push('bar');
$queue.push('baz');
my $index_of_foo = $queue{'foo'}; # undef if no foo in queue.
And what's to prevent that collection object from handling:
my $queue = SomeQueue.new;
$queue.push('foo');
$queue.push('bar');
$queue.push('baz');
my $index_of_foo = $queue['foo']; # undef if no foo in queue.
--
Garrett Goebel
IS Development Specialist
ScriptPro Direct: 913.403.5261
5828 Reeds Road Main: 913.384.1008
Mission, KS 66202 Fax: 913.384.2180
www.scriptpro.com [EMAIL PROTECTED]
RE: arrays, hashes unified indexing syntax impact on futurevariat ion s on other collection types [x-bayes]
From: Piers Cawley [mailto:[EMAIL PROTECTED]]
Garrett Goebel [EMAIL PROTECTED] writes:
And what's to prevent that collection object from handling:
my $queue = SomeQueue.new;
$queue.push('foo');
$queue.push('bar');
$queue.push('baz');
my $index_of_foo = $queue['foo']; # undef if no foo in queue.
Because I also want to be able to access
$nth_foo = $queue[$n]
Which I thought was so blindingly obvious as not to need stating.
Never underestimate blindingly obvious when I'm involved ;)
$idx_of_foo = $queue['foo']; # named lookup
$nth_foo= $queue[600]; # ordered lookup
One is SvPOK the other SvIOK...
Can't we handle both and still have the ordered lookup be fast?
--
Garrett Goebel
IS Development Specialist
ScriptPro Direct: 913.403.5261
5828 Reeds Road Main: 913.384.1008
Mission, KS 66202 Fax: 913.384.2180
www.scriptpro.com [EMAIL PROTECTED]
Re: arrays, hashes unified indexing syntax impact on futurevariat ion s on other collection types [x-bayes]
Garrett Goebel [EMAIL PROTECTED] writes:
From: Piers Cawley [mailto:[EMAIL PROTECTED]]
Garrett Goebel [EMAIL PROTECTED] writes:
And what's to prevent that collection object from handling:
my $queue = SomeQueue.new;
$queue.push('foo');
$queue.push('bar');
$queue.push('baz');
my $index_of_foo = $queue['foo']; # undef if no foo in queue.
Because I also want to be able to access
$nth_foo = $queue[$n]
Which I thought was so blindingly obvious as not to need stating.
Never underestimate blindingly obvious when I'm involved ;)
$idx_of_foo = $queue['foo']; # named lookup
$nth_foo= $queue[600]; # ordered lookup
One is SvPOK the other SvIOK...
Can't we handle both and still have the ordered lookup be fast?
No. Because in general we don't know what's in the brackets until
runtime. And then we don't know in what context to evaluate what's in
the brackets. Because, in Perl unlike in many other OO languages that
don't have a syntactic distinction between array and hash lookup, a
value can happily have both a numeric *and* a non-numeric value. Which
means that YOU CAN'T USE THE TYPE OF THE 'INDEX' OBJECT TO DETERMINE
WHETHER YOU'RE DOING A HASHLIKE OR AN ARRAYLIKE LOOKUP. As Dan pointed
out ages ago. The only reason I suggested that it didn't matter was
because I'd forgotten about the cases where having both arraylike and
hashlike behaviour was useful.
--
Piers
