Perl 5.10 and above have state variables, but they don't work for hashes and arrays - just scalars. Still, you can use hashrefs/arrayrefs.

sub encode {
    state $lookup = {
        '"' => '"',
        '&' => '&',
        '<' => '&lt;',
        '>' => '&gt;',
        map((chr($_), "&#$_;"), (0..31)),
    };
    state $re = do { my $tmp = join('', keys %$lookup); qr/([$tmp])/ }
+;
    
    my ($text) = @_;
    return '' unless defined $text;
    $text =~ s/$re/$lookup->{$1}/g;
    return $text;
}

[download]

If you need to support older versions of Perl, then curly braces can be used to limit the scope of lexical variables...

{
    my $lookup = {
        '"' => '&quot;',
        '&' => '&amp;',
        '<' => '&lt;',
        '>' => '&gt;',
        map((chr($_), "&#$_;"), (0..31)),
    };
    my $re = do { my $tmp = join('', keys %$lookup); qr/([$tmp])/ };
    
    sub encode {
        my ($text) = @_;
        return '' unless defined $text;
        $text =~ s/$re/$lookup->{$1}/g;
        return $text;
    }
}

[download]

Or even better (because it delays populating the variables until they're needed):

{
    my ($lookup, $re);

    sub encode {
        $lookup ||= {
            '"' => '&quot;',
            '&' => '&amp;',
            '<' => '&lt;',
            '>' => '&gt;',
            map((chr($_), "&#$_;"), (0..31)),
        };
        $re ||= do { my $tmp = join('', keys %$lookup); qr/([$tmp])/ }
+;
    
        my ($text) = @_;
        return '' unless defined $text;
        $text =~ s/$re/$lookup->{$1}/g;
        return $text;
    }
}

[download]
package Cow { use Moo; has name => (is => 'lazy', default => sub { 'Mooington' }) } say Cow->new->name

In reply to Re: Best Practice for replace sub by tobyink
in thread Best Practice for replace sub by Skeeve

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.