On Tue, 2004-05-18 at 18:16, Juerd wrote:
> St?phane Payrard skribis 2004-05-18 23:14 (+0200):
> > I use over and over this idiom in perl5:
> > $a{$_}++ for @a;
> > This is nice and perlish but it gets easily pretty boring
> > when dealing with many list/arrays and counting hashes.
I never saw the original, but in Perl 5, you would probably just define
a class which stored the information you needed. In Perl 6, it should be
much easier to make that class behave the way you want syntactically,
but for example in Perl 5 (wrap with tie to taste):
package CountedArray;
sub new { $obj=bless {}, $_[0]; $obj->push(@_) if @_; $obj }
sub fetch {
my $self = shift;
my $index = shift;
return $self->{array}[$index];
}
sub store {
my $self = shift;
my $index = shift;
my $data = shift;
my $old = undef;
if ($self->exists($index)) {
$old = $self->fetch($index);
$self->{counter}{$old}--;
}
$self->{array}[$index] = $data;
$self->{counter}{$data}++;
return $old;
}
sub exists {
my $self = shift;
my $index = shift;
return exists @{$self->{array}};
}
sub delete {
my $self = shift;
my $index = shift;
if ($self->exists($index)) {
$self->{counts}{$self->{array}[$index]}--;
delete $self->{array}[$index];
}
}
sub count {
my $self = shift;
my $data = shift;
return $self->{counter}{$data};
}
sub counts {
my $self = shift;
return %{$self->{counter}};
}
--
Aaron Sherman <[EMAIL PROTECTED]>
Senior Systems Engineer and Toolsmith
"It's the sound of a satellite saying, 'get me down!'" -Shriekback
