2009/11/18 Randal L. Schwartz <mer...@stonehenge.com>:
>
> I prefer a pattern that looks more like this:
>
> sub expensive_to_calculate {
>
> my $self = shift;
> my $input = shift; # cache on this scalar
>
> our %cache_for_expensive_to_calculate;
> return $cache_for_expensive_to_calculate{$input} ||= do {
> expensive calculation here;
> more things based on $input;
> last expression is value;
> };
>
> }
>
> Yes, in 5.10, this can be simplified, but I find 5.8 to still be
> the dominant Perl.
>
> This also presumes that a "false" value is never needed to be cached.
Hi,
Re-hashing an old thread here.
I've tried to borrow the above pattern for something I'm doing but I'm
wondering if this is going to work in the environment I working in.
It' is perl, v5.6.2, on a modperl 1, and the although the package is a
class, somehow the package/file I'm working with is being used in a
function-orientated way. Yes, it all needs updating but I need to get
this last feature in before I move it to new architecture.
sub get_prices_from_code {
my $code = shift;
our %cache;
return $cache{$code} ||= do {
my $sql = qq(SELECT DISTINCT price_code, price_id FROM prices);
my $dbq = dbiQuery($sql);
if ($dbq->success && $dbq->rows) {
while ( $dbq->fetch() ) {
if ($code eq ($dbq->row())[0] ) {
$code = ($dbq->row())[0];
$cache{$code} = ($dbq->row())[1];
}
}
return $cache{$code};
}
}
}
I guess the question is: Will the declaration of our %cache within a
function-orientated sub-routine render it always uninitialized?
Thanx,
Dp.
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