This Week on perl5-porters (6-12 January 2003)
The porters were busy, and this week's report features a large number of
different subjects, from portability and compilation to the proper
semantics of method dispatch, not forgetting the usual amount of strange
bugs. Read below about the latest potential evolutions of Perl 5.
Warning on UTF8 locales ?
In bug report #19743, Jarkko Hietaniemi summarized one of the main
problems with UTF8 locales. Under an UTF8 locale, perl 5.8.0 implicitely
turns on the UTF8-ness of input filehandles. Also, reading illegal UTF-8
data does not trigger any warnings; but later, trying to use the
resulting data does. This is annoying.
The proposed solutions are a combination of the following points :
* Don't turn on *silently* UTF8-ness of all filehandles; issue a
mandatory message (when the developer hasn't made clear he accepts
UTF8);
* Don't turn on automagically UTF8-ness of all filehandles; require
the script to have use()'d the locale pragma (or even a possible
"use locale qw(utf8)") to do so; (Ton Hospel later questions whether
the lexical scoping behavior of this pragma is well-suited to
solving this problem);
* Reading illegal UTF8 data from a filehandle marked as UTF8 should
issue a warning (but this is hard to achieve without slowing down
all input).
http:[EMAIL PROTECTED]/msg90565.html
Pathnames and Portability
There was quite a long thread, crossposted to perl5-porters and to the
Cygwin developers list, about the proper way to handle path names on
Cygwin (how it should deal with Windows-style and Unix-style pathnames,
and how the conversions should be done). This is related to definiting
the proper behavior of File::Spec::Cygwin. Among the points are : what
to do with pathologic cases (files names legal on Windows but not on
Cygwin), what exactly is an absolute path (it turns out that UNC paths
and paths that start with a single backslash are considered absolute on
Windows), etc. Then, the thread becomes verbose and off-topic.
http:[EMAIL PROTECTED]/msg90511.html
share() empties hashes
Barrie Slaymaker noticed (last month) that marking a hash reference as
"shared" clears the hash silently. Nick Ing-Simmons explains that it was
implemented that way by laziness and for speed : copying the hash
contents when sharing it means writing a internal routine to do this,
and that should be safe regarding potential reference loops and
already-shared internal data structures. Benjamin Goldberg suggests to
introduce a separate rshare() function which does this recursive
copying.
http:[EMAIL PROTECTED]/msg90536.html
is-a basic type
Piers Cawley asked why method dispatch doesn't work with basic types;
more precisely, while a blessed hashref is-a "HASH" (according to
"UNIVERSAL::isa()"), it's not possible to call methods from package
"HASH" on this blessed hashref. The discussion following this difficult
question spawns the territories of Perl 6.
http:[EMAIL PROTECTED]/msg90539.html
Profiler segfaults
Blair Zajac continued to investigate cases of segmentation fault within
the Perl profiler Devel::DProf. Apparently, increasing a fudge factor (a
stack size) solves his problems. (Ilya Zakharevich called this "voodoo
programming" but Benjamin Goldberg provided a more logical explanation
for it.)
http:[EMAIL PROTECTED]/msg90611.html
Latest Berkeley DB
Bug #19884, reported by Martin Mokrejs, is about building perl 5.8.0
with Berkeley DB 4.1.25. This doesn't work, because (quoting Paul
Marquess) "Perl 5.8.0 was released before Berkeley DB 4.1 came out.
There was a change in the Berkeley DB API that wasn't backward
compatible." The recommended solution is to build perl without DB_File
(by giving the "-Ui_db" command-line option to "Configure") and to
install later the latest DB_File from the CPAN.
http:[EMAIL PROTECTED]/msg90696.html
Old bug reopened
Six months ago bug #15479 was fixed (this was about the simple statement
%::="" leading to a core dump when warnings are enabled). John Peacock
remarks that the fix isn't good enough, because it doesn't work when
some operators are overloaded. John also makes a good job at trimming
down the cause of this bug.
http:[EMAIL PROTECTED]/msg90707.html
Sun's upcoming compiler
Alan Burlison (from Sun) told the Perl 5 porters about the upcoming
version of the Sun C compiler. This future version is expected to break
the hints file for Solaris in various ways (firstly, the detection of
the compiler version, secondly, checking the presence of the libsunmath
library). He volunteers to provide a patch.
http:[EMAIL PROTECTED]/msg90725.html
In brief
Rafael Garcia-Suarez proposes to ship a simple RPM spec file with perl.
Axel Thimm notes that this hides nasty portability pitfalls. He adds
that it might be interesting to try an LSB (Linux Standard Base)
packaged perl (see http://www.linuxbase.org/appbat/).
Rafael also changed the value of the internal variable "${^TAINT}", so
it's now 0 without taint checks, 1 with -T, and -1 with -t or -TU.
Previously it was only 0 or 1.
Ernest Lergon found bug #19767 pertaining to use of "\p{}" escapes
within character classes in precompiled regular expressions.
Peter Scott reported bug #19815, about an amusing syntax error that
confuses perl's lexer enough to make it unable to count lines properly.
Mark-Jason Dominus notices that fsync(2) is missing from the POSIX
module (bug #19860). However the functionality is provided by
IO::Handle::sync().
Brendan O'Dea sent a load of patches.
There are some smoke escaping from the Cygwin builds. Apparently Merijn
now installs bleading edge snapshots of Cygwin on the machine he runs
the some tests on.
About this summary
This summary brought to you by Rafael Garcia-Suarez. Summaries are
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