in reply to Reading Variables from a File

Here's what I use in my scripts. Say you have a text file named "config.txt" that looks like this:

# This is my configuration file
variable1=111
variable2=222

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I put this sub into my script to read that data back in:

sub GetSetting
{
my ($cfg_value,$cfg_filename,$cfg_default)=@_;
open(CFGFILE,"<$cfg_filename") or die "Can't open configuration file $
+cfg_filename.";
my @cf=<CFGFILE>;
foreach $cfg_line (@cf)
{
if (index($cfg_line,"#")==0) { next; } # Lines starting with a hash ma
+rk are comments
my @ln=split("=",$cfg_line);
if ($ln[0] =~ /$cfg_value/i) {
chomp $ln[1];
return $ln[1];
}
}
close CFGFILE;
return $cfg_default; # Return default if we can't find the value 
}

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You set the default value when you call the sub. To read the setting back in, just do like so:

my $setting = GetSetting('variable1','config.txt','111');

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Re: Answer: Reading Variables from a File
by Anonymous Monk on Jun 01, 2003 at 01:19 UTC

    I would submit that it is often better to read all the configuration information at once. Here's a snippet that uses this philosophy:

    use strict;
 
my(%config) =
("variable1" => "default1",
 "variable2" => "default2");
 
&get_settings("myconfig",\%config);
 
sub get_settings{
  my($filename,$config_hash) = @_;
  my($var,$val);
 
  return unless ref $config_hash eq "HASH";
 
  open(CFGFILE,"<$filename")
    or die "Cannot open config file $filename: $!";
  while (<CFGFILE>){
    chomp;
    next if /^#/;
    ($var,$val) = split(/=/,$_,2);
    $config_hash->{$var} = $val if exists $config_hash->{$var};
  }
  close(CFGFILE);
}

    [download]

    Of course, there's always Config::General, but it's probably overkill and you may not be able to count on it being there for you.

[reply]
[d/l]
      Part of the reason why I like to grab settings "on the fly" is because you can then change those settings at runtime. By grabbing the setting only when I need it, I can tweak the configuration file while the script is running. For settings that can't be changed while running, I load them in at the beginning of the script and store them in scalars.

      A genius writes code an idiot can understand, while an idiot writes code the compiler can't understand.
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