Why are variables declared with "our" visible across files?

Question

From the "our" perldoc:

our has the same scoping rules as my, but does not necessarily create a variable.

This means that variables declared with our should not be visible across files, because file is the largest lexical scope. But this is not true. Why?

Answer 1

You can consider our to create a lexically-scoped alias to a package global variable. Package globals are accessible from everywhere; that's what makes them global. But the name created by our is only visible within the lexical scope of the our declaration.

package A;
use strict;
{
  our $var; # $var is now a legal name for $A::var
  $var = 42; # LEGAL
}

say $var; # ILLEGAL: "global symbol $var requires explicit package name"
say $A::var; # LEGAL (always)

{
  our $var; # This is the same $var as before, back in scope
  $var *= 2; # LEGAL
  say $var; # 84
}