In Perl 4 the &sigil was mandatory, Perl 5 changed this.

IIRC it has now a bunch of side effects like°

• disabling prototype check when passing arguments
• reusing the caller's @_ when not passing arguments

This can be very useful in edge cases <1‰, but will more likely cause trouble in normal use.

The only time you can't avoid &sigils in standard Perl5 is when referencing a named function ˛

$code_ref = \&sub_name

More in perlsub ...

HTH :)

Updates

°) other use case are:

• calling a post-declared sub without parens().

  E.G. like when wanting to use AUTOLOAD while avoiding parenthesis for syntactic sugar.

• calling a sub named after a built-in

  E.g. CGI.pm used to have a sub &tr for HTML's "table row" tag which collided with Perl's tr (IIRC)

• ˛) some built-ins require & with named subs as arguments, like goto, map , grep , sort

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