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Postings from November 2021
On Wed, 10 Nov 2021 at 19:59, Ovid via perl5-porters <perl5-porters@perl.org>
wrote:
> Hi Porters!
>
> I would love to see a permanent keyword for Perl. It initializes a
> variable once and only once. It would look like this:
>
> #!/usr/bin/env perl
>
> use 5.38.0;
> use warnings;
>
> sub variables {
> my $name = shift;
> return sub {
> my $my = 1;
> state $state = 1;
> permanent $permanent = 1;
> say "$name: my is $my. state is $state. permanent is
> $permanent";
> $_++ for $my, $state, $permanent;
> }
> }
>
>
you can achieve described behaviour by moving "permanent line" into parent
scope:
sub variables {
my $name = shift;
state $permanent = 1;
return sub {
my $my = 1;
state $state = 1;
say "$name: my is $my. state is $state. permanent is $permanent";
$_++ for $my, $state, $permanent;
}
}
Extrapolating your idea - it will be imho better to be able to specify
variable "in scope", eg:
sub variables {
SCOPE:
my $name;
return sub {
state $state;
# expressing intention not suggesting syntax
UPPER SCOPE { state $permanent }
}
}
it will allow to concise for example phaser blocks, current state:
my $foo;
BEGIN { $foo = 'bar' };
BEGIN { UPPER { my $foo = 'bar' } }
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