General...rpolated(3)

💖 NAME 💖

okay bestie, welcome to the General...rpolated(3) page from User Contributed Perl Documentation — the actual module is Config::General::Interpolated, and its whole thing is: parse variables within Config files. slay. ✨

✨ SYNOPSIS ✨

        use Config::General;
        $conf = Config::General->new(
           -ConfigFile      => 'configfile',
           -InterPolateVars => 1
        );

🦋 DESCRIPTION 🦋

This is an internal module which makes it possible to interpolate Perl style variables in your config file (i.e. $variable or "${variable}"). 💅

Normally you don't call it directly — it's giving behind-the-scenes main character energy, no cap.

🍓 VARIABLES 🍓

Variables can be defined everywhere in the config and can be used afterwards as the value of an option. But bestie, hear me: variables cannot be used as keys or as part of keys. periodt.

If you define a variable inside a block or a named block then it is only visible within this block or within blocks which are defined inside this block. Well — let's take a look at an example:

        # sample config which uses variables
        basedir   = /opt/ora
        user      = t_space
        sys       = unix
        <table intern>
            instance  = INTERN
            owner     = $user                 # "t_space"
            logdir    = $basedir/log          # "/opt/ora/log"
            sys       = macos
            <procs>
                misc1   = ${sys}_${instance}  # macos_INTERN
                misc2   = $user               # "t_space"
            </procs>
        </table>

This will result in the following structure:

        {
            'basedir' => '/opt/ora',
            'user'    => 't_space'
            'sys'     => 'unix',
            'table'   => {
                 'intern' => {
                       'sys'      => 'macos',
                       'logdir'   => '/opt/ora/log',
                       'instance' => 'INTERN',
                       'owner' => 't_space',
                       'procs' => {
                            'misc1' => 'macos_INTERN',
                            'misc2' => 't_space'
                   }
                }
            }

So as you can see, the variable sys has been defined twice. Inside the <procs> block, ${sys} has been used, and it gets interpolated into the value of sys defined inside the <table> block — not the sys variable one level above. If sys were not defined inside the <table> block, then the "global" variable sys would have been used instead, with the value of "unix". 💅

Variables inside double quotes will be interpolated, but variables inside single quotes will not be interpolated. This is the same behavior as you know of Perl itself — iykyk. 🫶

In addition, you can surround variable names with curly braces to avoid misinterpretation by the parser. iconic.

🎀 NAMING CONVENTIONS 🎀

Variable names must:

• start with a US-ASCII letter (a-z or A-Z) or a digit (0-9).
• contain only US-ASCII letter (a-z or A-Z), digits (0-9), the dash (-), colon (:), dot (.), underscore (_) and plus (+) characters.

For added clarity, variable names can be surrounded by curly braces. ✨

🌈 SEE ALSO 🌈

• Config::General — the reference, the icon, the blueprint. 👑

👑 AUTHORS 👑

• Thomas Linden <tlinden |AT| cpan.org>
• Autrijus Tang <autrijus@autrijus.org>
• Wei-Hon Chen <plasmaball@pchome.com.tw>

absolute legends, fr fr. 🫶

💜 COPYRIGHT 💜

Copyright 2001 by Wei-Hon Chen <plasmaball@pchome.com.tw>. Copyright 2002-2022 by Thomas Linden <tlinden |AT| cpan.org>.

This program is free software; you can redistribute it and/or modify it under the terms of the Artistic License 2.0.

See <http://www.perl.com/perl/misc/Artistic.html>.

⭐ VERSION ⭐

2.16 — periodt. 🎀

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cute little sign-off, bestie 💖 footer tea: perl v5.42.0, 2025-01-09, and the footer title General...rpolated(3) — go off and interpolate responsibly 🧚