sub cgiapp_prerun {
    my $self = shift;
    my $q = $self->query();
    if    ($q->param("file")) { $self->prerun_mode('file') }
    elsif ($q->param("db"))  { $self->prerun_mode('db') }
    elsif ($q->param("mmdw"))  { $self->prerun_mode('mmdw') };
}

#!/usr/bin/perl
sub sub_1 { die }
my $event = {
     'src'           =>  \&sub_1(q|attrib_1|),
     'file'          =>  \&sub_2(q|attrib_2|),
     'keyword'       =>  \&sub_3(q|attrib_3|),
};

$ /tmp/bla.pl
Died at /tmp/bla.pl line 2.
Exit 255

tina@lux:~> perl -MData::Dumper -wle'
sub test { 23 };
$sub = \&test;
$sub2 = \&test("param");
print Dumper $sub, $sub2'
$VAR1 = sub { "DUMMY" };
$VAR2 = \23;