After reading perlsub#Overriding-Built-in-Functions

> To unambiguously refer to the built-in form, precede the built-in name with the special package qualifier CORE:: .  For example, saying CORE::open() always refers to the built-in open()

You should probably simply call CORE::sleep()

Have you tested if CORE::GLOBAL::sleep() even exists before overriding? *

Cheers Rolf
(addicted to the Perl Programming Language :)
Wikisyntax for the Monastery

update

*) nope it doesn't

update

see also an explanation how to fix it with exists

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

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