Hi,

I have been using state to cache a hashref and I am unsure whether this is good usage. It does however work.

Here is an example of usage: 

#!/usr/bin/perl
use v5.10;
use strict;
use warnings;

sub example_sub {
    my $cfg = cfg_cache();
    say $cfg->{x};
}

sub cfg_cache {
    state $cfg = shift;
    return $cfg;
}

my $cfg = { x => "cat"};

cfg_cache($cfg);

## "cat" gets printed
example_sub();

## "mouse" gets printed.
$cfg->{x} = "mouse";
example_sub();

## but if I reset $cfg "mouse" still gets printed
$cfg = { x => "rat"};
example_sub();

[download]

example_sub() always gets whatever the current contents of $cfg should be as long as $cfg is not reset.

Without reading from cfg_cache() example_sub() has no access to the $cfg hashref.

The state perldoc says "variables will never be reinitialized" but it doesn't cover what happens if the variable is a reference.

Is this good practice?

I am using Perl 5.18 on Debian Unstable but using state this ways works from v5.10

In reply to caching hashrefs in state by agname

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