This is a question about a perl5 feature I could find no documentation about so far. I would be glad to know whether it is intended this way and safe to use or even recommended.

A bareword ending in a double colon, such as Foo::Bar::, evaluates to a string without the double colon suffix, "Foo::Bar" in this example. Using such a bareword is not prohibited under strict 'subs', but it triggers a warning if perl hasn't seen a package of that name yet.

Example: 

use strict;
use warnings;
package Foo::Bar;
package main;
my $p = Foo::Bar::;
print "$p\n";         # prints Foo::Bar
my $q = Baz::Qux::;   # warns:
# Bareword "Baz::Qux::" refers to nonexistent package
print "$q\n";         # prints Baz::Qux

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I'll call this feature package-name-quoting, as appending two colons has the effect of quoting plus package name validation. I could use it where package name strings are needed, such as in arguments for isa or DOES. The warning would help me to catch typos.

So, after all, it is a useful feature. Is it documented? I would have expected perlmod to say something about it. Maybe I looked in the wrong place.

In reply to Bareword Package Names by martin

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