This week on the Perl 6 mailing lists
"Take the longest token, lie down and if the unease persists, write
some code..."
-- Brad Bowman, in 'DFA/NFA context is non-local <http://xrl.us/uqix>'
perl6-language
RAII in Perl6/Parrot <http://xrl.us/tz2r>
Previously on this thread, Blair Sutton asked if Perl 6 would be able
to do RAII. He cited some articles which expressed the view that it
was not possible in Python due to the fact that garbage collection
does not offer deterministic finalization. This led to the question of
whether Perl 6 would suffer from the same problem due to Parrot's
style of garbage collection.
Larry Wall replied that deterministic reference counting was only one
way to provide transactional security and timely destruction. He
assured Blair that Perl 6 has ways to let you not care about some
dependencies, while paying attention to others.
Blair appreciated Larry's explanation, and admitted to relying on the
deterministic nature of C++, and using RAII to manage locks between
threads and tear apart sockets cleanly. He asked for an example of
Perl 6 offering the capability to execute code once every reference to
an object has been removed. Luke Palmer replied that the LEAVE closure
trait was a general method for addressing this.
This week, Blair posted a script in Perl 5 with a multi-threaded RAII
idiom. Blair asked if the LEAVE closure trait takes the previous role
of P5's DESTROY or if it will always be executed when one falls out of
scope.
Numeric Semantics <http://xrl.us/t3o7>
Last week, the subthread was further expanded, with TSa suggesting
that all rounding functions such as floor, round and trunc take an
optional second argument which defines the jump size. TSa also
proposed a number of division function pairs, such as fdiv and fmod
for flooring division and modulus, or tdiv and tmod for truncating
division and modulus. Smylers felt that this would introduce far too
many functions in to the Perl core, given that few people would use
them. Smylers felt that it was more appropriate to have them as
modules. Jonathan Lang added that it was unlikely anyone would need
multiple definitions of division and modulus at any given time, so
modules made sense. The only question he saw was which definition was
default, the mathematically elegant one or the industry standard one.
The main thread was revived when TSa replied to Luke Palmer's question
of whether 1 is different from 1.0. TSa wanted 1 to be an Int and 1.0
to be a Num. There was some discussion with Jonathan Lang over the
relationship between Int and Num, specifically which one does the
other.
This week, Larry Wall put his foot down and stated that the default
`/` operator is not going to do integer division and that this is not
negotiable. Later in the thread, Larry said that for various practical
reasons, he didn't think that Int can be treated as a subset of Num.
He agreed that `1.0 == 1 !=== 1.0`.
Larry's messages generated praise from Smylers, but TSa was not
satisfied. However, he did not receive a noteworthy response this
week.
[svn:perl6-synopsis] r13523 - doc/trunk/design/syn <http://xrl.us/uqim>
This commit message by Larry Wall logged the following: "Tweak `|` to
provide longest-token instead of short-circuit semantics. Now use `||`
for old short-circuit semantics!" In a follow-up message, Larry
elaborated:
This checking majorly changes the semantics of `|` within regex to
support required longest-token matching semantics rather than
left-to-right matching. It will enable us to write parsers more
consistently, and it also opens up normal regexes to better
optimization via tries and such. You can now use `||` for the old `|`
semantics, which is majorly consistent with how `|` and `||` work
outside of regexen.
Patrick Michaud asked if a similar situation would arise for `&`
versus `&&`. Larry answered that, for reasons of consistency, that
would indeed be the case.
The S13 "is commutative" trait <http://xrl.us/uqin>
After reading that binary operators may be declared as commutative,
Dave Whipp asked if this is restricted to only binary operators, or if
he could tag any function/method with the trait. After a brief
discussion, Larry replied that he had decided "is commutative" must
die of ill-definedness. See instead the recent S13 change to support
multiple signatures on a single body.
[svn:perl6-synopsis] r13529 - doc/trunk/design/syn <http://xrl.us/uqit>
This commit, by Larry Wall, changes how regular expressions are
analyzed. They are seen as pattern/action pairs and grammars as
collections of those pairs. In addition 'token' is defined more
rigorously.
Remember: Outlaw to declare a lexical twice in the same scope
<http://xrl.us/uqiu>
Steve Lukas reminded people of a proposal from September which
involved a change on S04 and linked to an earlier edition of this
summary to describe the conclusions which had been reached. He
requested that the changes be made. Carl M??sak added that he also
considered this to be an important issue. He wanted to see a warning
when a lexical is declared twice in the same scope.
Dave Mitchell and Smylers clarified how it works in Perl 5 (it's
possible, but generates a warning).
DFA/NFA context is non-local <http://xrl.us/uqix>
Brad Bowman expressed his concern about the context dependence of DFA
prefix mode. He felt this might be because he hadn't yet digested the
new rules completely.
Smooth or Chunky? <http://xrl.us/uqi7>
Larry Wall asked for some advice with a missing generalization that he
hadn't been able to work out yet. Given that `zip` and `each` produce
similar results, he wondered what is the use of two functions which do
almost the same thing. This led him to believe that zip should return
something different and let the context determine whether the result
should be flattened. This led to musings on a default smooth and an
optional chunky, and a question on whether chunky should be the
default when it makes more sense. He suggested various options.
Darren Duncan thought that the Perl 5 approach of default 'smooth'
with optional 'chunking' was appropriate. As an example he offered the
smooth `map { $_, $_ * 10 }, 1..3` versus `map {[$_, $_ * 10]}, 1..3`.
Larry replied that this was one function where the approach was
possible, but that Perl 5 has many places where it fails to scale well
to a multi-programmer team.
Ruud H.G. van Tol believed that it looked like a 'multiple faces'
domain. He sees the dimensionally structured data as a living entity
which should give different representations depending upon the
requirements. As an example, he cited a meal, a recipe and a shopping
list, adding that his preference was for the shopping list to be
ordered by where things are found in the store. Brad Bowman suggested
that the dimensional information should be retained, but that it might
not need to be returned.
Ben Morrow proposed `[[]]` as a nice visual way to indicate that a
list should be built. Blair Sutton listed several possible syntax
options. Austin Frank joined in, offering the outverse of `[;]`,
namely `];[`.
Map on a multislice <http://xrl.us/uqja>
Joe Gottman wanted to know if map on a multislice performs deep or
shallow iteration. He wanted to know what the default iteration level
was and how to override it. Dr. Ruud added that there's also the
option of depth first or width first.
perl6-internals
[perl #41185] [BUG]: examples/shootout/regexdna.pir.input: Persistently
failing test <http://xrl.us/t78e>
Earlier, in ticket [perl #41185] <http://xrl.us/t78f>, James Keenan
reported a problem with a failing test in `shootout.t` on Mac OSX.
This week he reported that tests had passed for several weeks, but had
recently started to fail again. He included the output of `make test`.
As of February 6th, the test was still failing on Darwin.
Re: [perl #41230] [BUG] t/codingstd/perlcritic.t uses too many resources
<http://xrl.us/uqjc>
Earlier, Jerry Gay complained that the perlcritic coding standards
test was using resources, and asked in ticket [perl #41230]
<http://xrl.us/t9n4> if someone could look in to this problem. Paul
Cochrane reported that he thought there was a memory issue relating to
`critique()` and that the memory was only freed up when the tests for
a given policy are complete. Paul elaborated on what what he had
attempted to address the issue.
This week Jerry Gay congratulated Jeffrey Thalhammer on version 1.01
of Perl::Critic, which solved the memory issue.
[perl #41267] [TODO] rename 'clip' pdd directory to 'draft'
<http://xrl.us/ucn6>
In ticket [perl #41267] <http://xrl.us/ucom>, Jerry Gay announced that
the `clip` directory had been renamed to `draft`.
[perl #41280] [PDD] adding methods to subs as objects
<http://xrl.us/uqjd>
In ticket [perl #41280] <http://xrl.us/u2yx>, Allison Randal quoted
Patrick Michaud from IRC. Patrick explained that Larry Wall's most
recent change to S05 would require adding the ability to attach
methods to subs.
[perl #32667] [PATCH] IMCC - documentation needs updating
<http://xrl.us/uqje>
Bram Geron included a patch in ticket [perl #32667]
<http://xrl.us/u2yy> which adds new syntax to `docs/imcc/syntax.pod`
and fixes some typos. It also references where flags are explained. It
was applied as r16678.
More embedding questions <http://xrl.us/uqjf>
Isaac Freeman explained that he needs an embedding interface which
allows more control over the interpreter and cited some examples of
control he required. He asked specifically about the ability to
inspect and modify namespaces. chromatic pointed him to PDD 21, which
is not completely implemented.
repository open for commits <http://xrl.us/uqjg>
Jerry Gay announced that the repository was now open for commits
again, following the recent Parrot release.
[perl #41287] [PATCH] fix 0.4.8 announcement on parrotcode.org
<http://xrl.us/uqjh>
Allison Randal created a ticket ([perl #41287] <http://xrl.us/u2yz>)
with a patch to fix typos in the release announcement for 0.4.8. Will
Coleda applied it.
[perl #41291] [BUG} Can't use null PMC with :multi sub
<http://xrl.us/uqji>
In ticket [perl #41291] <http://xrl.us/u2y2>, Matt Diephouse included
an example piece of code demonstrating the problem. Leopold Toetsch
noted that a NULL PMC was never actually specced, but that he did
consider it like a NULL pointer in C. He felt it was debatable whether
the use Matt demonstrated should be allowed.
[perl #41292] [PATCH] make languages/cola/{lexer,parser}.c comply with
coding standards <http://xrl.us/uqjj>
In ticket [perl #41292] <http://xrl.us/u2y3>, James Bence submitted a
patch to make the test `t/codingstd/trailing_space.t` pass. He felt it
would be best to make a utility program which would eliminate trailing
spaces.
Paul Cochrane asked which version of Parrot James was using, as the
files involved should be marked as exempt because they are
automatically generated. In r16702 the tests pass even without the
patch.
Tcl, trace, profiling... <http://xrl.us/uqjk>
Will Coleda announced that he had two issues with the new Tcl
implementation: speed and the implementation of `trace`. After noting
that there is a way to set traces for Parrot subroutines, he requested
the ability to declare hooks to call pre- and post sub invocations.
Ideally these could be declared at compile time. He offered to write
more complete specifications if the idea was interesting to others.
Allison Randal offered a few comments and requested the detailed
proposal. Jerry Gay advised looking at Perl 5's Hook::LexWrap.
Klaas-Jan Stol offered a suggestion which would leave the original
subroutine untouched.
[perl #41293] [BUG]: t/compilers/tge/basic.t: Failed during 'make test'
but passed with 'prove' <http://xrl.us/uqjm>
James Keenan reported a failing `make test`. This was ticket [perl
#41293] <http://xrl.us/u2y4>.
How handle the next parameter of invoke method in a PMC ?
<http://xrl.us/uqjp>
Fran??ois Perrad stated that in Lua, a metamethod `__call` is required.
He included some code demonstrating what he would like to do, and
noted that the code and some todo tests had been added.
[perl #41310] [CAGE] autogenerated PMC stubs kill compile
<http://xrl.us/uqjq>
Allison Randal created ticket [perl #41310] <http://xrl.us/u2y5>. She
reported that PMC stubs which are generated with
`tools/dev/gen_class.pl` terminate the compilation the first time
miniparrot is run because the new stub overrides the `namespace`
method. She suggested ways in which this might be solved.
[perl #41312] [TODO] - Docs - update FAQ <http://xrl.us/uqjs>
In ticket [perl #41312] <http://xrl.us/u2y6>, Will Coleda pointed out
several outdated facets of the FAQ and requested that they be fixed.
[perl #41317] [PATCH] parrot component/interface stability
classification <http://xrl.us/uqjv>
In ticket [perl #41317] <http://xrl.us/u2y7>, Jerry Gay included a
patch of a document classifying Parrot component and interface
stability. He requested comments. Allison Randal approved of the
document.
[perl #41320] [PATCH] Added rename() method to os.pmc
<http://xrl.us/uqjw>
Ticket [perl #41320] <http://xrl.us/u2y8> contained Kay-Uwe Huell's
patch with a `rename` function. It was applied as r16771.
[perl #41323] [CAGE] convert C<theINTERP> to C<interp>
<http://xrl.us/uqjx>
Jerry Gay made a ticket ([perl #41323] <http://xrl.us/u2y9>) where he
noted that any instances of `theINTERP` should be spelled as `interp`.
Nuno Carvalho submitted a patch, which was applied as r16789. Jerry
Gay was able to confirm that it worked for Win32 in addition to Linux.
[perl #41324] [PATCH] Eliminate '//'-style comments <http://xrl.us/uqjy>
Andy Dougherty submitted a patch to remove `//` comments, which were
giving problems with his compiler. See ticket [perl #41324]
<http://xrl.us/u2za> for more information.
[perl #41325] [PATCH] Fill in missing pointer cast in
<http://xrl.us/uqjz>
Andy Dougherty submitted a patch to allow Parrot to compile on his old
Sun C compiler. He put it in ticket [perl #41325]
<http://xrl.us/u2zb>.
[perl #41326] [PATCH] Work around an optimization bug in Sun's WorkShop
Compilers 4.2 <http://xrl.us/uqj2>
In ticket [perl #41326] <http://xrl.us/u2zc>, Andy Dougherty submitted
a patch to work around an obscure bug in Sun's WorkShop Compilers 4.2.
[perl #41328] [BUG] pmc2c generates unnecessary code for void functions
<http://xrl.us/uqj3>
Jerry Gay reported some warnings when compiling `src/pmc/pmethod.c` in
ticket [perl #41328] <http://xrl.us/u2zd>. James Keenan explained the
origin of the code in question, and advised moving the code to a
branch until tests prove it suitable for trunk.
[perl #41329] [BUG]: Imposition of coding standards breaks tests in
t/tools/pmc2cutils/ <http://xrl.us/uqj4>
James Keenan noted, in ticket [perl #41329] <http://xrl.us/u2ze>, that
coding standards tests break some tests in `t/tools/pmc2cutils`. He
believed that it happened in r16751, when code was changed to conform
with the standards but wasn't run against the tests and submitted a
patch to correct the problem. Paul Cochrane explained that he had run
the tests, but that he hadn't done enough, and apologized.
[perl #41331] Imposition of coding standards breaks tests in tcl.
<http://xrl.us/uqj5>
In ticket [perl #41331] <http://xrl.us/u2zf>, Will Coleda referenced
an earlier thread ([perl #41329] [BUG]: Imposition of coding standards
breaks tests in t/tools/pmc2cutils/ <http://xrl.us/uqj4>) which
mentioned that some tests failed as a result of coding standards being
applied. Several Tcl tests were failing. They were fixed by r16774.
__init vs. __init_pmc <http://xrl.us/uqj6>
Leopold Toetsch noted that some changes not too long before the
release had broken `pg.t`. He found the problem in the object
constructor, and mentioned that he'd made several attempts to unify
object construction but that it wasn't very successful.
Matt Diephouse explained that he had made the change with Allison
Randal's approval, to eliminate differences between PMCs and objects.
Leopold replied that he thought the differences were confusing but
that they still were. He linked to his proposal for method calling
<http://xrl.us/u2zg>.
[PATCH] PIR language using PGE (2) <http://xrl.us/uqj7>
Klaas-Jan Stol submitted a patch for PIR using PGE. Jerry Gay applied
it (with minor changes) as of r16831.
[perl #41353] [PATCH] Extended very limited PIO_unix_pipe() function in
src/io/io_unix.c <http://xrl.us/uqj9>
Kay-Uwe Huell created ticket [perl #41353] <http://xrl.us/u2zh>.
Included was a patch to extend the `open` function.
perl6-compiler
Parrot 0.4.8 Released <http://xrl.us/uqka>
Jerry Gay announced the release of Parrot 0.4.8, "Eponymous".
Jarkko Hietaniemi questioned whether there was in fact extended
support for Tru64, as he had only reported problems for subsystems
like PGE. chromatic offered Jarkko commit access, but Jarkko declined.
Matt Diephouse volunteered to work on Tru64 if someone could give him
access to a system. Nicholas Clark replied that HP gave access to a
number of test systems, but not Tru64. Jarkko grumbled about HP's
restriction. Unfortunately he was not able to provide a developer with
Tru64 access. He thought that perhaps development on any 64-bit
platform would already improve Parrot.
Acknowledgements
This summary was prepared using Mail::Summary::Tools
<http://xrl.us/qvno>, available on CPAN.
If you appreciate Perl, consider contributing to the Perl Foundation
<http://donate.perlfoundation.org> to help support the development of
Perl.
Thank you to everyone who has pointed out mistakes and offered
suggestions for improving this series. Comments on this summary can be
sent to Ann Barcomb, <[EMAIL PROTECTED]>.
Distribution
This summary can be found in the following places:
* use.perl.org <http://use.perl.org/>
* The Pugs blog <http://pugs.blogs.com/>
* The perl6-announce mailing list <http://xrl.us/qycj>
* ONLamp <http://www.oreillynet.com/onlamp/blog/>
See Also
* Perl Foundation activities <http://blog.perlfoundation.org>
* Perl 6 Development <http://dev.perl.org/perl6>
* Planet Perl Six <http://planetsix.perlfoundation.org/>
