General::Interpolated(3)                   User Contributed Perl Documentation


NAME
       Config::General::Interpolated - Parse variables within Config files

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.

VARIABLES
       Variables can be defined everywhere in the config and can be used
       afterwards as the value of an option. Variables cannot be used as keys
       or as part of keys.

       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 to 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'
                   }
                }
            }

       As you can see, the variable sys has been defined twice. Inside the
       <procs> block a variable ${sys} has been used, which then were
       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 interpolated. This is the same behavior
       as you know of Perl itself.

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

NAMING CONVENTIONS
       Variable names must:

       o   start with a US-ASCII letter(a-z or A-Z) or a digit (0-9).

       o   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

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

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

perl v5.38.0                      2023-07-25          General::Interpolated(3)