This Week on perl5-porters - 8-14 September 2008

This Week on perl5-porters - 8-14 September 2008

   "A string in Perl is a sequence of arbitrarily large integers. If they
   are all < 256, then you can store them all in bytes, so you can use a
   sequence of bytes. If some of them of them are > 255, then you need a
   representation that allows storing such values, and a byte string is
   not enough. In that case, Perl stores a sequence of variable-width
   values encoded according to the rules of UTF-8." -- Aristotle
   Pagaltzis, making it seem so simple.

Topics of Interest

The great "perl589delta" race!

   Paul Fencwick has put together a mailing list, RSS feeds, a repository
   and more for people wishing to help write the document describing the
   changes in perl 5.8.9. Most importantly, he wrote a micro HOWTO to
   show people how they could get involved (and no, you don't need to
   read p5p, nor this summary in order to help).

     no more excuses
     http://xrl.us/oru6d

   In a related note, Andy Dougherty expunged the INSTALL file of
   references to 5.10.

     http://xrl.us/oru6f

Wrong debugger interaction with 'n' single stepping and a panic

   Heiko Eißfeldt didn't like the way the perl debugger doesn't know how
   to leap over entire "map" or "grep" blocks in a single leap when using
   the 'n' command. In fact it was enough to make Heiko to make the
   debugger Do The Right Thing, and proposed a patch for review. Joshua
   ben Jore offered some good advice for making things more robust,
   especially when taking error handling into account.

     source perlmonks thread
     http://www.perlmonks.org/?node_id=709679

     richard foley offers encouragement
     http://xrl.us/oru6h

"unless(...)" terser than "if(!...)"

   In response to Graham Barr's counter-example using overloading that
   showed then "if(!$foo)" is not equivalent to "unless($foo)", Nicholas
   Clark commented that this was sufficient reason not to integrate the
   change into a minor release, as there may be code out there that
   relies on an overloaded variable being true and false at the same
   time.

   On the other hand, the concept is so demented that he had no qualms in
   breaking it for a major release.

     another obfu bites the dust, hep hep
     http://xrl.us/oru6j

   Steve Hay bemoaned the fact that the unless/!if optimisation blew away
   his "Win32API::File" smokes. Vincent Pit realised that he had failed
   to make allowance for chained nots, as in "1 if !$x or !$y or !$z",
   since that exceeded the size of the opcode stream that the peephole
   optimizer was able to consider. And, bad luck, such a code path was
   tweaked in test.pl itself. (Hint: we need some absurd chains of
   conditional tests somewhere in the test suite).

   Nevertheless, according to the theory that being able to describe the
   bug means you're able to fix it, Vincent proposed a second patch that
   nullifies the ops rather than trying to surgically remove them.

     no ops bad, null ops good
     http://xrl.us/oru6m

Storable-2.15 on FC9

   J. Adams was suffering in the attempt to build an ancient version of
   Storable (2.15) on a brand new 5.10 perl. Nicholas Clark asked if this
   was really necessary, since the current 2.18 is so much nicer. J.
   replied that yes, it was vital, since other machines in the network
   with older versions of Storable were digesting the output and would
   fail if they encountered Storable files from the future.

   Nicholas sketched out what brain transplant surgery would be required
   in order to get things to work. We may assume that J. succeeded in
   getting things to work.

     http://xrl.us/oru6o

"Test::Harness" prove.t failures

   Steve Hay discovered that all his smoke tests were failing simply
   because he had set the "HARNESS_TIMER" environment variable to 1.
   Nicholas Clark stole some code from Andy Lester's upstream
   "Test::Harness" repository that he hoped would address the problem.

     http://xrl.us/oru6q

blead with "-Dusemymalloc" fails on t/comp/hints.t

   Vincent Pit noticed that blead is now failing in the above test file
   but had no idea since when. A little detective work led him to
   conclude that it was a question of underlying C "struct"s that were
   running into a problem of overlapping copies. While neither Rafaël
   Garcia-Suarez nor Nicholas were able to reproduce the error, Vincent's
   patch seemed sane enough to apply.

     http://xrl.us/oru6s

Capture the wtf8 flag

   (Best. Subject. Line. Ever.)

   Ricardo Signes joined a long list of illustrious Perl hackers in
   experiencing the pain of UTF-8, and suggesting a set of guidelines for
   dealing with it. Aristotle Pagaltzis laid it out in crystal clear
   terms (see the top of this article). Glenn Linderman tweaked
   Aristotle's looser prose and both of them recommended Juerd Waalboer's
   "BLOB" CPAN module that helps in times like these.

   More advice from Glen Lindemann:

   *   Using the utf8 flag to make decisions about how to process
       character data is inappropriate.

   *   Using the utf8 flag to determine if it is character data or not is
       inappropriate.

   So don't do that.

     http://xrl.us/oru6u

2038 fix

   Michael G. Schwern is dragging Perl kicking and screaming into the mid
   21st century, so that date arithmetic in the years 2039 and beyond
   won't collapse in a screaming heap on Unix systems. People with more C
   expertise than Michael are invited to join in the fun on the Google
   Code project that hosts the code that deals with this.

     your children will be grateful
     http://xrl.us/oru6w

   Michael had so much fun with 2038 and git branching that he went ahead
   and produced a git branch for grafting 2038+ date arithmetic onto
   blead.

     http://xrl.us/oru6y

   In the process of dealing with time values larger than 32 bits,
   Michael wondered about scalar upgrades that go from signed to unsigned
   "int" and thence to "double", and whether it would be worth slotting a
   64-bit long long in there somewhere.

   Joshua Hoblitt suggested the Utopian int to long long to
   "Math::BigInt". Tels, as author and maintainer of "Math::BigInt"
   pointed out that he had collected various ideas and techniques over
   the years to rewrite it in C, but said that this would take hundreds
   of hours and he didn't see how the effort could be financed, short of
   winning the lottery.

     http://xrl.us/oru62

$VERSION in "Opcode"

   Nicholas Clark wondered how one should deal with different versions of
   "Opcode" living on CPAN (insofar as it is published with each released
   version of Perl) whilst avoiding "I must upgrade your perl" arms race
   when someone attempts to upgrade it.

   Rafaël thought it was pretty much a non-issue, given that Opcode is so
   intimately tied to the particular perl release (unlike "Safe" which is
   dual-life-clean), it cannot reasonably be upgraded. In light of this,
   its version number is nearly meaningless. Nicholas wondered if a
   "1.06_01" scheme could work.

   Zefram recalled problems with "Module::Build" in the light of such
   version numbers, but John Peacock thought that "Module::Build" no long
   had any issues relating to development release numbering schemes.

     http://xrl.us/oru64

"Test::Smoke" improvements for Windows

   Jan Dubois, answering Steve Hay's question as to why his smokes spewed
   so many warnings, said that the main problem is that the smoke in
   question is on a 64-bit platform, even though there's precious little
   in the output to distinguish it from a 32-bit build.

   The warnings arise from the fact that Perl's internals are not 64-bit
   clean at all. Variables are defined as I32 (32 bits in length) and get
   assigned "size_t" values (which are indeed 64 bits in length on 64-bit
   platforms), plus many other assorted programming sins.

   Other 64-bit platforms are more or less immune to such problems as
   everything is 64 bits. Windows is singular in its approach, with
   "int"s and "long"s being 32 bits when "IV"s and pointers are 64 bits.
   Jan had tried to clean this up once, but wound up converting just
   about every single "I32" into an "IV".

   Andy Dougherty felt his pain, having undertaken the same task himself
   in days gone past. After having battled to resolve the contradictions
   between perl's own internals use of an "int", and what the C library
   wants to see in terms of "int", each time Andy found something much
   easier to do, like rewriting Perl's Unicode handling on EBCDIC.

     http://xrl.us/oru66

Change 33727 (op.c) breaks constant folding in "elsif"

   Alexey Tourbin uncovered a flaw in the plan to fix the longstanding
   "wrong line number reported for "elsif"" bug. Nicholas understood why
   it was going wrong, but professed lack of knowledge to figure out how
   the optree and peephole optimiser work.

   Vincent Pit proposed a fairly ambitious patch to blead that fixed this
   issue which Rafaël applied to blead. At the same time, Rafaël also
   thought that the original patch was too dangerous to go into the 5.8
   track at least in its current state and it being so close to the 5.8.9
   release. Nicholas concurred, and backed the change out.

     http://xrl.us/oru68

O(1) ISA isa not as great as hoped

   Nicholas Clark related the story of Tim Bunce profiling "PPI" with
   "Devel::NYTProf", and discovering that "PPI" spends 15% of its time
   living in "UNIVERSAL::isa".

   So he replaced an @ISA linear scan with a hash lookup. And then he
   wondered why he observed only a 1% speed improvement. Michael G.
   Schwern thought that the problem was probably not so much @ISA
   traversals something going on in "isa_lookup", which contains a lot of
   code.

     http://xrl.us/oru7a

"pod2man" and POD errors (cpan #39007)

   Russ Allbery asked what the porters thought of changing "pod2man"'s
   error handling to emit errors to stderr, rather than building a POD
   ERRORS section in the document. He listed the pros and cons of each
   approach.

   Alan D. Salewski voted for stderr, Zefram suggested an option to
   "die()" on error.

     podchecker anyone?
     http://xrl.us/oru7c

TODO of the week

   Here we go, this is easy. Fame, fortune, it's all yours.

merge checkpods and podchecker

   pod/checkpods.PL (and "make check" in the pod/ subdirectory)
   implements a very basic check for pod files, but the errors it
   discovers aren't found by podchecker. Add this check to podchecker,
   get rid of checkpods and have "make check" use podchecker.

Patches of Interest

Fix up minor formatting inconsistency in "perltodo"

   When looking for the TODO of the week a couple of weeks ago, several
   proof-readers pointed out the POD formatting errors in the TODO
   section. As it was a direct steal from perltodo.pod, I sent in a patch
   to fix it up. But of course Nicholas Clark did a much better job of
   it.

     fwp -- fun with pod
     http://xrl.us/oru7g

Fix mismatched "#if"/"#endif" in Win64 configuration.

   Jan Dubois suspected that change #33350 was responsible for deleting
   an "#ifdef" from a Windows header file. So he put it back, and Rafaël
   applied the change.

     http://xrl.us/oru7i

$ENV{TEST_JOBS} vs $ENV{HARNESS_OPTIONS}

   Bram dug down to the bottom of a problem with the new test harness
   running tests in parallel and having some tests fail because they are
   not yet parallel-safe.

   He thought that the problem was that "Tap::Harness" was not running
   certain tests serially because of interactions between two environment
   variables that govern the harness. So he wrote a patch to get the test
   suite testing without error, which seemed good enough for Rafaël to
   apply.

     http://xrl.us/oru7k

Cross-compilation - step 1 of N+1

   Vadim Konovalov delivered a first patch, to Makefile.SH, in hopefully
   what will be a series, to get cross compilation working. The result of
   the patch is a new Makefile target which can then be used to kick off
   the compilation. Rafaël seemed pleased.

     http://xrl.us/oru7n

Fix parallel testing temp filenames

   Jerry D. Hedden identified lib/charnames.t, lib/strict.t and
   lib/subs.t as badly behaved citizens in the brave new world of
   parallel testing, so he adjusted them to use the officially sanctioned
   temporary file name generation technique.

     the prognosis is grim
     http://xrl.us/oru7p

     conform or die
     http://xrl.us/oru7r

New and old bugs from RT

CGI "multipart_init()" incorrectly quotes other headers (#33118)

   Steve Peters filed a bug in 2004 concerning a problem that the
   Bugzilla project had uncovered with the venerable CGI.pm.

   Renée Bäcker wrote a patch to address the problem, but it broke the
   test suite. In the time it took him rework the patch, Lincoln Stein
   had already fixed it in his upstream repository.

   While this was happening Nicholas Clark piped up to get the
   attribution of another Windows patch from Steve Hay sorted out in the
   credits. Craig A. Berry also confirmed that the VMS patches that
   Lincoln had integrated blindly did in fact result in a clean test run
   for VMS.

     3.42 is gold
     https://bugzilla.mozilla.org/show_bug.cgi?id=275108
     http://xrl.us/oru7t

Subclassing "CGI::Pretty" dies in ->new (#41572)

   Nicholas Clark noted with satisfaction that as of CGI version 3.42,
   the blead and CPAN versions are byte-for-byte identical. The only
   scheduled change planned in blead is simply the architectural issues
   involved in placing the CGI build directory under ext/, which should
   not affect the source.

     http://xrl.us/oru7v

print doesn't overwrite $! (#43097)

   Christoph Bussenius wrote a patch to fix this problem, which simply
   clears the error flag on the file descriptor each time it's called.

   Gisle Aas pointed out the flaw in the plan. Christoph took another
   stab at solving the problem, but realised that with a global $!,
   there's not much chance at developing a robust solution. What's needed
   is a $! for each file handle.

     http://xrl.us/oru7x

debugger: "o warn=0 die=0" ignored (#57016)

   Tye McQueen reported that, following a refactoring of the debugger
   that assigned the functionality of "O" to "o", the above debugger
   command no longer did anything useful. He restored the previous
   behaviour (or some sort of useful behaviour) in a patch, which Rafaël
   Garcia-Suarez applied.

     http://xrl.us/oru7z

"Unicode::UCD::casefold()" does not work as documented (#58430)

   In response to Karl Williamson's description of the possible options
   available to him to solve the problem of Unicode case folding, David
   Landgren offered a couple of suggestions.

     http://xrl.us/oru73

unicore/mktables expects wrong syntax from CaseFolding.txt (#58656)

   As Karl kept looking at the Unicode problems, he discovered that the
   "mktables" program, which generates the Unicode tables that the core
   will use afterwards, is looking for things in a file that Karl points
   out do not exist. He wasn't sure whether the code is just utterly
   wrong, or whether the Unicode Consortium changed the contents of the
   file at some point. Either way, something needs to be done about it.

     http://xrl.us/oru75

POD for "encoding" pragma has triplicated section (#58774)

   Darren Duncan suggests that of the three "Side effects" section in the
   documentation, only one is needed.

     do not operate heavy machinery
     http://xrl.us/oru77

make test problem, perl 5.10.0 on AIX 6.1 (#58802)

   G. Harders reported a problem building NDBM on AIX. Unfortunately, all
   the sympathetic AIX hackers were busy doing other things.

     http://xrl.us/oru79

Not OK: perl 5.11.0 +DEVEL +patchaperlup: on i686-linux-64int 
2.6.22-1-k7 (UNINSTALLED) (#58848)

   The problem is that "Test::Harness" is looking for, and failing to
   find "Time::HiRes".

     http://xrl.us/oru8b

Perl5 Bug Summary

     264 new + 1032 open = 1296 (+8 -5)
     http://xrl.us/oru8d
     http://rt.perl.org/rt3/NoAuth/perl5/Overview.html

In Brief

Kawaljeet Kaur reported encountering a couple of errors building
"Time::HiRes" with perl 5.8.8 on a justifiably ancient Solaris 2.6
host. Steve Peters was more impressed by the fact that such an old
operating system was able to build a recent Perl with no more errors
than that.

     teaching an old dog new tricks
     http://xrl.us/oru8f

   Richard Srisamang mulled over a "Storable" problem, whereby a data
   structure is read in, the structure acquires additional elements and
   then is written out... and the new file is smaller than the original
   file. Nicholas Clark suggested viewing the results in a human-readable
   format, such as XML (sniggering not allowed) or "Data::Dumper".

     sounds like a feature
     http://xrl.us/oru8h

   Tom "spot" Callaway is desperately seeking Rob Brown (BBB on CPAN).
   It's a question of licensing code on CPAN with respect to Fedora.

     licensing issues, yummy yummy!
     http://xrl.us/oru8j

   Gábor Szabó is clearly mad, since he's building a GUI front-end to run
   debugger sessions over a network link.

     and looking for a name
     http://xrl.us/oru8m

Last week's summary

This Week on perl5-porters - 25-31 August 2008

   Where it is given thanks for the work of Bram and Renée Bäcker in
   reducing the bug count by several hundred over the summer.

     http://xrl.us/oru8o

This Week on perl5-porters - 1-7 September 2008

   No comments.

     http://xrl.us/oru8q

About this summary

   This summary was written by David Landgren.

   Weekly summaries are published on http://use.perl.org/ and posted on a
   mailing list, (subscription: [email protected]). The
   archive is at http://dev.perl.org/perl5/list-summaries/. Corrections
   and comments are welcome.

   If you found this summary useful, please consider contributing to the
   Perl Foundation or attending a YAPC to help support the development of
   Perl.

-- 
stubborn tiny lights vs. clustering darkness forever ok?