Question

I have written a Perl script to read the configuration file and create CGI scripts. This works fine and I get the output of CGI script on terminal and I can execute that CGI scripts on web pages. Below is my sample script.

#!/usr/bin/perl -w

use strict;
use Text::Template;

my $conf = "test.cfg";

open CFG, $conf or die "Could not open config file";
my @rawConfig = <CFG>;
my $config = eval "{".join("",@rawConfig)."}";

my $template = Text::Template->new(TYPE => 'FILE',  SOURCE => 'test.cgi.tmpl');
my $result = $template->fill_in(HASH => $config);
print $result;

By using this I have to save each of the CGI and execute separately. I need help to modify this code so that I can directly execute this script on web and display the output on webpage.

Answer 1

Multiple template based scripts is (almost) never the right answer.

Use data structures from a config file and control structures to get the behaviors you need.

Instead of using a template to create code like:

sub foo {
    my $thing = shift;

    return blarg( $thing ) * feemb( $thing );
}

sub bar {
    my $thing = shift;

    return crag( $thing ) * forg( $thing );
}

sub baz {
    my $thing = shift;

    return chomb( $thing ) * veezle( $thing );
}

Do this:

# Get this from a config file.  YAML perhaps
my $cfg = {
    foo => [ \&blarg, \&feemb  ],
    bar => [ \&crag,  \&forg   ],
    baz => [ \&chomb, \&veezle ],
};

sub calculate_product {
    my $cfg   = shift;
    my $type  = shift;
    my $thing = shift;

    my @subs_to_call = @{ $cfg->{$type} || [] };

    my $result = {shift @subs_to_call}->($thing};

    $result *= $_->($thing) for @subs_to_call;

    return $result;
}
# Call like so:
my $foo_prod = calculate_product($cfg, 'foo', 15);

You can bind config info to a subroutine (that is ‘curry your functions’) by generating closures with config info:

# Get this from a config file.  YAML perhaps
my $cfg = {
    foo => [ \&blarg, \&feemb  ],
    bar => [ \&crag,  \&forg   ],
    baz => [ \&chomb, \&veezle ],
};

my %calculate_product;
for my $product ( keys %$cfg ) {

    my @stored_subs_to_call = @{$cfg->{$product} || [] };

    $calculate_product{$prod} = sub {
        my $thing = shift;

        my @subs_to_call = @stored_subs_to_call;

        my $result = {shift @subs_to_call}->($thing};

        $result *= $_->($thing) for @subs_to_call;

        return $result;
    }
}

# Call generated code like so:
my $foo_prod = $calculate_product{foo}->(15);