Great work by both of you, and the possible syntax tricks nicely show TIMTOWTDI, but the original motive for trying LIST += LIST was a hoped-for performance gain from the interpreter completing the whole set in one opcode, instead of add...add...add....

I suspect that overloaded objects like this will cause problems if used in inner loops. :-) Neat tricks, though...

> will cause problems if used in inner loops

performance won't be great unless implemented in XS.

But that's the way I would implement new features in Perl.

• a nice syntactic sugar which does the job in pure Perl and stays fully backwards compatible.
• speed it up in XS for newer versions
• if it becomes popular, consider including it into CORE.

Cheers Rolf
_{(addicted to the Perl Programming Language :)
Wikisyntax for the Monastery}

Even with an XS implementation, you will still have the dispatch overhead for the overloaded operator. Eventually including it in core perl would allow the parser to resolve the dispatch at compile-time, but until then I wonder how long the list needs to be to make up that difference?