I hava a perl subroutine where i would like to pass parameters as a hash (the aim is to include a css depending on the parameter 'iconsize').

I am using the call:

get_function_bar_begin('iconsize' => '32');

for the subroutine get_function_bar_begin:

use strict;
...
sub get_function_bar_begin
{
    my $self = shift;
    my %template_params = %{ shift || {} };

    return $self->render_template('global/bars   /tmpl_incl_function_bar_begin.html',%template_params);
}

Why does this yield the error message:

Error executing run mode 'start': undef error - Can't use string ("iconsize") as a HASH ref while "strict refs" in use at CheckBar.pm at line 334

Am i doing something wrong here? Is there an other way to submit my data ('iconsize') as a hash?