Perl Subroutine Declaration Unexpected Symbols

Question

I have been looking at some Perl code that has some subroutine declarations that make no sense to me. They appear as:

foo($$$$;$);
foo(\$\$\$);

What do the symbols ";" and "\" do or mean in these declarations?

score 5 · Accepted Answer · edited Jun 27 '17 at 15:32

5

They're "prototypes" - but Perl prototypes aren't like those in other languages, and probably shouldn't be used.

The $ denotes a scalar argument to the function. ;$ denotes an optional additional scalar argument. And \$ denotes a reference argument.

edited Jun 27 '17 at 15:32

Sinan Ünür

answered Jun 27 '17 at 13:47

Sobrique

2

[Obligatory "why prototypes are bad" link](https://stackoverflow.com/questions/297034/why-are-perl-5s-function-prototypes-bad) – mob Jun 27 '17 at 13:48
Pilfered and edited into the answer. – Sobrique Jun 27 '17 at 14:05

1 Answers1