The Perl 6 Summary for the week ending 20030202
Welcome to the second Perl 6 summary of the Copious Free Time era and
already I've broken the 'mailed out by Monday evening' promise. There
were reasons however, mostly to do with going down to London to do the
paperwork for my redundancy stuff. So, I'm emending the promise to
'mailed out by logical Monday evening'.
Starting with perl6-internals (which was pretty quiet this week, only 76
messages compared to perl6-language which tipped the scales with 162)
Parrot Objects (noun, not verb)
Piers Cawley worried about class private attributes and asked it it was
still going to be possible to write an object serializing tool that
wouldn't require tons of Perl class overloads. Dan said that it should
still be possible.
<http://makeashorterlink.com/?R34F24653>
The packfile patches, an ongoing saga.
Leo Tötsch spent the week working on the packfile format and Parrot's
tools for manipulating it. Various internals folks provided feedback,
pointers to standards and other handy feedback.
<http://makeashorterlink.com/?V25F31653>
<http://makeashorterlink.com/?G47F21653>
<http://makeashorterlink.com/?W28F35653>
<http://makeashorterlink.com/?O19F21653>
Securing Parrot ASM
Thomas Whateley has been thinking about how to allow Parrot to run
untrusted code in a sandbox, and proposed a system where code would
provide a list of required rights and Parrot would guarantee that only
those privileges were provided. Matthew Byng-Maddick pointed everyone at
the RFC he'd written along these lines and raised the issue of what
happens when you call out to a module that's written natively, which he
described a 'brick wall'. Others were less sure that this was a
showstopper.
Somewhat annoyingly my mailer seems to have had a bad moment and lost
some messages, including one from Dan in which he outlined his vision
for 'safe mode' and gave some pointers to the VMS docs in this area.
<http://makeashorterlink.com/?W3AF52653>
<http://dev.perl.org/rfc/353.pod>
<http://makeashorterlink.com/?D2BF12653> -- Dan's outline
Parrot Developer World Map
Leon Brocard announced the Parrot Developer World Map, which plots the
locations of all the Parrot developers who sent him their location
details on a map of the world. A cursory glance at the map would seem to
imply that a good place for a Parrot Developers' face to face meeting
would be a Caribbean island. Gregor neatly one upped Leon with his
interactive SVG version.
<http://www.astray.com/parrot/worldmap/>
<http://makeashorterlink.com/?O2CF12653>
Coroutine context patch
Jonathan Sillito found some problems with the coroutine code, so he
wrote a test exposing the errors, patched things to fix the errors and
added a documentation patch to be on the safe side. Go Jonathan. Steve
Fink applied the patches. Jonathan also had a question about naming, and
wondered if anyone would be interested in a howto for compiler writers.
Nobody commented on this, but the howto sounds like a great idea to me.
<http://makeashorterlink.com/?T4DF21653>
Multiple code segments and the interpreter
Leo Tötsch noted some problems with "interpreter->code" and multiple
code segments, suggested a way forward and asked for comments. Nicholas
Clark commented, wondering about the potential for memory leaks but Leo
seemed to think that that was covered.
<http://makeashorterlink.com/?Q3EF15653>
Parrot run loop problems
Leo has also been thinking about Parrot run loops and reckons we're
doing it wrong. So he proposed a different way of doing things, working
through its impact on the various kinds of Parrot core. Steve Fink liked
Leo's idea, but Jason Gloudon was less sure.
<http://makeashorterlink.com/?T1FF53653>
Meanwhile, in perl6-language
More Array Behaviours
Michael Lazzaro is working on documenting Perl Arrays and asked for
confirmations and clarifications on various areas of Array behaviour.
One subthread morphed into a discussion of when to use "is" properties
and when to use "but" properties. It turns out that the '"is" is compile
time, "but" is runtime' rule of thumb is only a rule of thumb. Damian
says that a better distinction is '"but" is a property on a value, "is"
is a property on a referent'. Variables, arrays, opaque objects, hashes
etc are referents and therefore get "is" properties. Values are thing
things that are held in variables, arrays, opaque objects etc, and they
get "but" properties.
<http://makeashorterlink.com/?O20021753>
Spare Brackets
Martin wondered if it would be possible to use "[]" to do both hash and
array lookups. Short answer "No". Which isn't to say the thread didn't
take off like a runaway train. After far too many messages we reached
the same 'No' conclusion that Damian had stated way back a the start of
the thread. The reasoning goes like this: Given $container[$spec] you
can't use the type of $container to decide whether to do a hash or an
array lookup because there are Perl object types which have both hash
and array semantics. And you can't use $spec's type either because Perl
happily autoconverts between numbers and strings. So, you need some way
to specify what sort of lookup you need, and you do that by using "{}"
or "[]" as appropriate. But, frankly, that's beside the point. The
reason we're not using "[]" to do both array and hash style lookups is
Because Larry Says So.
<http://makeashorterlink.com/?U21012753>
<http://makeashorterlink.com/?W52023753>
Arrays: Default values
Argh! I've really been screwed by problems with my mail here. For some
reason a batch of mail appears to have got dropped on the floor this
week and my record of this thread is the one that's suffered the most.
The gist of the thread is that adding a default value to an array opens
a whole scary can of worms to do with the distinction between 'undef'
and 'exists' (made trickier still by the fact that 'exists' is a pretty
vague concept when you're dealing with an array.) Damian's view is that
an array with a default value should do the equivalent of
$content = @foo[$index] // @foo.default;
ie, all undefs in the array should be 'replaced' with the array's
default value. And that includes any 'deliberate' undefs (where the
programmer does "@foo[$index] = undef"). As I understand it, doing
anything else leads to implementation pain. And it leads to even more
fun when your default is computed and the function doing the computation
gets passed the index as an argument. What happens when someone does a
shift?
For some reason this led into a discussion of whether hashes are ordered
(they're not, but if you leave a particular hash alone any iterators
(keys/values/each) will step through the hash in the same order,
repeatably, but that order is not predictable).
<http://makeashorterlink.com/?B33012753>
<http://makeashorterlink.com/?I14026753> -- Current 'default' rules
Damian Takes a Sabbatical
Damian announced that, owing to time pressures, the need to find paying
work, the need to help Larry get the next Apocalypse out the door and to
get the associated Exegesis written he's unsubscribed from the language
list for the time being, though he expects that he'll probably
resubscribe once A6 and E6 are released. Folks wished him well.
<http://makeashorterlink.com/?Y55015753>
In Brief
After asking for suggestions of a language to implement using parrot, K
Stol announced that he would be implementing a Lua->parrot compiler as
his final year project.
Who's Who in Perl 6?
Who are you?
Gopal V [gopalv82 at symonds dot net]
What do you do for/with Perl 6?
I'm more interested in Parrot rather than in Perl 6 , since it is
the only really free bytecode format out there. I am planning to
build a C# to Parrot compiler. I did a bunch of opcodes in this
direction , but mostly what I do is lurk around in the mailing list
& IRC.
Where are you coming from?
I'm from the DotGNU project and have been playing around in that
code for some time. I've still got my foot placed firmly there and
am peering over the hedge into parrot. I'm still in college, so I
still have to find time to study.
When do you think Perl 6 will be released?
On a Saturday morning after announcing Tuesday afternoon in the
release plan.
Why are you doing this?
It's great to be involved with a community project , it's a very
entertaining, stimulating and educating experience. In short, I'm in
this for the warm fuzzy feeling !.
You have 5 words. Describe yourself.
compulsive hacker, caffeine addict, RSI_sufferer.
Do you have anything to declare?
I promise, I'll try hard to get the C# compiler working with parrot.
(starts singing "Some day, Some way..." off key)
Announcements and Acknowledgements
This week's summary was once again prepared in a comfortable chair with
plenty of Earl Grey tea and distractions from two delightfully ginger
kittens and my embarrassing ability to screw up my Gnus installation
(now unscrewed).
Thanks to Gopal V for his answers to the questionnaire this week. If
you've been involved in the Perl 6 development process, please consider
answering the same set of questions and sending them to [EMAIL PROTECTED]
and you'll earn my undying gratitude.
Proofreading was handled by the ever lovely Aspell.
If you appreciated this summary, please consider one or more of the
following options:
* Send money to the Perl Foundation at
<http://donate.perl-foundation.org/> and help support the ongoing
development of Perl.
* Get involved in the Perl 6 process. The mailing lists are open to
all. <http://dev.perl.org/perl6/> and <http://www.parrotcode.org/>
are good starting points with links to the appropriate mailing
lists.
* Send feedback, flames, money, job offers or a working teleportation
device to [EMAIL PROTECTED]
This week's summary was sponsored by Darren Duncan. Thanks Darren. If
you'd like to become a summary sponsor, drop me a line at
[EMAIL PROTECTED]
--
Piers
