I prefer a symbol table lookup. 
perl -e '
  package Foo; 
  sub bar{42}; 
  package main; 
  print defined *Foo::bar{CODE}'
1

[download]
This avoids ambiguity issues with using the ampersand.
print+qq(\L@{[ref\&@]}@{['@'x7^'!#2/"!4']});

In reply to Re: How to check if a function exists within a package? by codeacrobat
in thread How to check if a function exists within a package? by rapide

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