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The Perl 6 Summary for the week ending 20031221

Welcome one and all to the penultimate Perl 6 Summary for 2003. The nights are long, the air is cold, freezing fog made the journey home from watching The Return of the King a deeply fraught experience (though probably not as fraught for us as for the chap who obviously didn't see the roundabout in time and went straight over it).

If you're in the southern hemisphere, feel free to ignore the foregoing flavour text.

It should come as no surprise to you by now that we start with the internals list.

Namespaces II

Dan returned from a bout of paying work to finish up the current understanding of how namespaces are managed in Parrot. A namespace selector becomes a multidimensional key (using a multidimensional key instead of a single long namespace name makes for easier sharing of namespaces between languages; there's no need to go guessing what separator the other language uses in its namespace naming because that's essentially irrelevant at the Parrot level). Looking up a particular variable in a namespace is still a two step process, first get the namespace, then do the lookup within the namespace. Dan explained that this is a win because it should allow for holding onto namespaces in a register when dealing with multiple variables.

Leo Tötsch wasn't entirely convinced by the new syntax introduced, and proposed a mechanism which used the standard syntax for accessing multikeyed structures with a proposed Namespace PMC.[]

Another keyed ops proposal

Leo continues to make proposals for rethinking keyed ops. Somewhat surprisingly, Dan didn't entirely reject the latest one involving a possible new set of key registers.[]

Leo adds threads

Leo Tötsch checked in a patch to allow Parrot to spawn threads. As he admitted, there's a lot missing, but it's a start. He solicited comments and further pointers.

Later in the week he asked for some design decisions related to making various of the interpreter's internal data structures thread safe. Elizabeth Mattijsen had several comments to make, based on experience with Perl 5's ithread system. In essence her suggestion was that as many things as possible should be made copy on write between threads. (I have a faint recollection of Nicholas Clark delivering a wonderful lightning talk/dance explaining his proposal for making Perl 5 use copy on write structures for ithreads. It's worth seeing if you get the chance...)

PDD03 and method calls

Leo queried the design of Parrot's calling conventions for calling a method and proposed a slightly different convention with the object put in P5 rather than P2. Dan thought that the calling conventions documented was the right way to go, but didn't seem to convince everyone.

Rolling back clone

Leo pointed out that clone's semantics had got altered to take an uninitialized destination PMC as an argument back when the GC system was flaky. He suggested switching back to a version that creates the new PMC itself now that GC was working properly. Dan told Leo to go for it.

Meanwhile, in perl6-language

Um... sorry about this, but I'm punting on writing the promised Roles/Traits/Classes summary. I was planning on doing it today, but things have been hellish; I've spent about 8 hours fighting fires today rather than writing the summary. Sorry.

Work on Perl 6's object system continues apace though; things are looking very good and powerful.

By the way from now on I'll try and stick to Larry's usage of capitalizing 'Traits' when referring back to the Traits paper, and keeping it lower case when referring to Perl 6's compile-time traits.

Runtime CHECK?

Piers Cawley asked if Perl 6 modules that get loaded at runtime will have their CHECK blocks (or their equivalent) executed. Larry initially thought not, but Rafael Garcia-Suarez noted that Perl 5 shouldn't be held up as exemplary and that there was definitely a need for some kind of special block that would get run at the end of the compilation phase of any arbitrary compilation unit.

but true

Adam D. Lopresto wondered how the recent work on Roles, Properties and Traits fit in with already declared stuff like but true. Larry confessed that he was still thinking hard about this, but that he thought but wasn't powerful enough yet.

Acknowledgements, Announcements, Apologies

Cross your fingers and toes, we might have link shortening in this version. Hurrah!

Merry Christmas everyone.

I make no promises about whether there will be a summary next week. Nor do I make any promises about whether there'll be a summary of the year (but I wouldn't hold your breath).

If you find these summaries useful or enjoyable, show your appreciation by contributing to the Perl Foundation to help support the ongoing development of Perl. Money and time are both good. I'm always pleased to get feedback at [email protected]'>p[email protected] and traffic at my website. -- The Perl Foundation -- My website, Just a Summary