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Re^3: Copy a builtin sub to a different name and then overrideby Haarg (Priest) |
on Jun 03, 2018 at 10:27 UTC ( [id://1215774]=note: print w/replies, xml ) | Need Help?? |
This isn't checking if CORE::GLOBAL::sleep exists, it's forcing it to exist. It's another form of autovivification. Taking a reference to a nonexistent sub like this will create a stub in its place (like sub CORE::GLOBAL::sleep;). A stub of course isn't callable. The correct way to check for the existence of a sub is using either exists &Some::sub or defined &Some::sub. exists will return true for subs that exist, even if they are stubs. defined will return true only for not-stub subs.
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