#!/usr/bin/env perl -wl
use strict;
sub x { return "ex" }
sub y { return "why" }
print y( $foo );
print x( $foo );

##</code><code>##

#!/usr/bin/env perl -lw
use strict;
package Test;
sub if  { return  "if($_[-1])" }
sub log { return "log($_[-1])" }
BEGIN {
    *main::if= \&if;
    *main::log= \&log;
}
my $foo= 1;
$_= 'Oops!';
$|= 1;

print if( $foo );
print Test->if( $foo );
print log( $foo );
print '';

package main;
print if( $foo );
print main->if( $foo );
print log( $foo );

##</code><code>##

Ambiguous call resolved as CORE::log(), qualify as such or use & at - line 16.
Oops!
if(1)
0

Oops!
if(1)
log(1)