#
# Usage:
# sub config {
#     my ($self, $config) = (shift, @_);
#     UpdateHash($self->{CONFIG}, $config);
# }
sub UpdateHash {
    my ($CONFIG, $config) = @_;
    $CONFIG = {} unless ref($CONFIG) eq "HASH";
    $config = {} unless ref($config) eq "HASH";
    for my $param (keys %$config) {
        if (ref($config->{$param}) eq "HASH") {
            $CONFIG->{$param}={} if ref($CONFIG->{$param}) ne "HASH";
            UpdateHash($CONFIG->{$param}, $config->{$param});
        } else {
            $CONFIG->{$param} = $config->{$param};
        }
    }
    return $CONFIG;
}
#
# Example
#
my $main = {};
UpdateHash( $main, {
   PARAM1 => "value1",
   PARAM2 => 15,
   } );
UpdateHash( $main, {
   PARAM2 => 123,
   PARAM3 => {
       DATA1 => "value31",
       DATA2 => "value32",
       },
   } );
UpdateHash( $main, {
   PARAM3 => {
       DATA2 => "newvalue32",
       },
   } );
# Here $main is equal to this :
# {
#  PARAM1 => "value1",
#  PARAM2 => 123,
#  PARAM3 => {
#      DATA1 => "value31",
#      DATA2 => "newvalue32",
#      },
# }