Notes
Please send corrections and additions to perl-thisweek-YYYYMM@simon-cozens.org where YYYYMM is the current year and month. Changes and additions to the perl5-porters biographies are particularly welcome.
This was a reasonably busy week, seeing just over 400 messages.
Many thanks to Leon for taking over these summaries in my absence.
More -Wall fixes
Doug MacEachern has been furiously fixing up compiler warnings this
week, tidying up
ext/ so that it is less noisy under
-Wall.
One major problem was that if an XSUB has no arguments and all the work
is done in PP code, the helper variable
ax is likely to be unused; Doug added a macro,
PERL_UNUSED_VAR, to wrap around
ax in such cases to prevent
xsubpp creating code that produced warnings.
Nick Clark also produced a mega (141K) warning-satisfying patch.
Dough also fixed up some missing
dTHXes in some of the extensions. This led to an associated change in
ExtUtil/Constant.pm, Nick Clark's helper module for creating the
constant subroutine in XS modules. It took a while for people to get their heads
around the idea that this was a Perl module that spat out XS code -
unfortunately, MakeMaker doesn't like the idea of having two
.xs files in a module, so you can't have a separate file for constants;
hence, you have to do evil things like modifying the XS code produced
by
h2xs in place. Urgh.
Miscellaneous Darwin Updates
Wilfredo Sanchez and Larry Schatzer have been our Mac OS X heroes this
week. They uncovered a bunch of problems, some of which have even been
fixed. Firstly, PerlIO was intercepting a warning from the locale system
before it had been properly initialized, and was causing segfaults.
There were also some numeric problems with
INT32_MIN - Apple's
stdin.h defines it as being -2147483648 instead of the more gcc-friendly
-2147483647-1. As Jarkko said, the real long-term fix would be to
fix Apple's header files; unfortunately, we can't do that very easily,
so we have to work around to redefining
INT32_MIN on Darwin ourselves.
Hash accessor macros
Abhijit Menon-Sen asked why
hv.c does things like
register XPVHV* xhv;
...
xhv = (XPVHV*)SvANY(hv);
... use of xhv->xhv_* ...
instead of simply
SvFOO(hv);
which is considerably easier to grep for. He then sent seven large patches which revert to the macro behaviour. Jarkko applied the patches, but then found that this generated a bunch of new warnings, and some nasty errors on HPUX.
Doug MacEachern piped up, saying that the original code was there for
reasons of performance; direct access saves a couple of indirections every
time one of the
xhv_ fields is accessed. He also said that the first
xhv = (XPVHV*)SvANY(hv);
might be stored in a register, optimising further accesses. Both Mike Guy and Ilmari Karonen suggested reverting to the previous optimised format, but putting in the macro version as comments so that they can be grepped for. Spider was called in to fix up the HPUX indigestion.
Abhijit also threw in some updates to
dump.c, and removed the tests in the core for "anonymous stashes" - a concept
which didn't even appear to exist...
iThreads development
Artur's been busy this week with iThreads support; he's working on a
number of different areas. Firstly, the continuing conversion of the
Threads.pm module for iThreads. His new module will be called
threads.pm and will soon appear on CPAN once he's finished writing test cases.
Another tack was to make regular expressions safe in threaded
environments, but that seems to have temporarily ground to a halt.
His big achievement this week was the implementation and documenting
of the
CLONE method, a callback like
DESTROY called on all objects when a thread is cloned. This caused some brief
problems on Win32 because of the way it was detecting stashes. Stashes
are, of course, normal hashes, so you have to be careful to call the
CLONE method from a stash, rather than do something horrible like attempt
to call the
CLONE entry from a hash. Nick added
if (gv_stashpv(HvNAME(hv),0)
as a guard, and it all worked again.
Cross-compilation
Jarkko has reported that the basics of cross-compilation support are working; he built miniperl for iPAQ by constructing an SSH tunnel, sending the binaries produced by Configure across and reading back the results. Read about it.
SV Documentation
God of the week award goes to Dave Mitchell. Over on the Perl 6 lists,
I'd asked for people to look through the Perl 5 sources and see what
sort of things happen to SVs, so that I could see what needed to happen
for Perl 6. In doing so, he produced 800 lines of documentation and
comments for
sv.c. Wow.
On his travels, he asked some questions about SV macros; the answers may be interesting. Read about it.
Various
Ilya put in a couple of scary patches for OS/2, including one which made Configure self-modifying. This was considered to be a Bad Thing.
Jarkko integrated the NetWare modifications to Perl, and the
Memoize module.
Sean Teague announced that the
Perl Power Tools can be downloaded from CPAN as
Bundle::PPT.
Chris Nandor updated
File::Find and its tests to cope with MacOS; however, this consisted mainly of
several iterations of
if (macos) {
A
} else {
B
}
which Jarkko balked at. Thomas Wegner rewrote the test suite to be much more maintainable.
Mike Guy noticed that many of the internal functions don't support
UTF8 strings properly; an important culprit is
Perl_warner, which means every warning or error message containing UTF8 data
gets mangled. He wants something which sanitizes a string for display.
Any takers?
Peter Prymmer hacked
h2ph to deal with C trigraphs - you remember them, the evil convention of
using, say, "??=" instead of "#". Urgh. He also fixed up some of the
extensions to build more happily under VMS. Craig Berry also chipped in
some extension patches for VMS.
Until next week I remain, your humble and obedient servant,
Mark-Jason Dominus
