This is not exactly what you asked for, but it is an 'approved' way to meet your requirement. Refer to the section "Overriding Built-in Functions" in perlsub 
use strict;
use warnings;
use subs 'sleep';

my $total_sleep_time;
sub sleep (;$) {
    $total_sleep_time += $_[0];
    CORE::sleep($_[0]);
}

sleep(2);
sleep(3);

print $total_sleep_time;

[download]
Bill

In reply to Re: Copy a builtin sub to a different name and then override by BillKSmith
in thread Copy a builtin sub to a different name and then override by bliako

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