#!/usr/bin/perl
use strict;
use warnings;

my %config = (
  page => {
    tmpl => q{page.tmpl},
    params => [qw{title param1 param2}],
  },
  layout => {
    tmpl => q{layout.tmpl},
    params => [qw{title param3 param4}],
  },
);

my %all_params = (
  title => q{title},
  param1 => q{param1},
  param2 => q{param2},
  param3 => q{param3},
  param4 => q{param4},
);

my %page_params   = map {$_ => $all_params{$_}} @{$config{page}->{params}};
my %layout_params =  map {$_ => $all_params{$_}} @{$config{layout}->{params}};

print Dumper \%page_params;
print Dumper \%layout_params;