use diagnostics;
use strict;
use warnings;

my @randomParameters = ('Abc.123', '../../', 'a@b.c', '789');
my @allowedSymbols   = ('.', '@');
my (@goodParams, @badParams);

checkParam($_, 1, 1, @allowedSymbols) for (@randomParameters);

print $_, " is good\n" for @goodParams;
print $_, " is bad\n"  for @badParams;

sub checkParam {
    my $param   = shift;
    my $alpha   = shift; # if true allow alpha
    my $numeric = shift; # if true allow numeric
    my @symbols = @_;    # allow all symbols in @_

    my $regex = "";

    $regex .= '([a-zA-Z' if $alpha;
    $regex .= '0-9'      if $numeric;

    for my $symbol (@symbols) {
        $regex .= $symbol;
    }
    $regex .= ']*)';

    my $pattern = qr/^${regex}$/;

    if ($param =~ /$pattern/) {
        push(@goodParams, $param);
    } else {
        push(@badParams, $param);
    }


}