Perl allows one to omit the parens of sub call, but doing so causes problems. In particular, problems surface where barewords are involved because barewords are treated specially by many parsing rules. "+" has no effect at run-time, but it can influence the parser by using it in a spot where a bareword would be otherwise.

In reply to Re: What does a plus mean before a package name? by ikegami
in thread What does a plus mean before a package name? by will_

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