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[perl #95538] perldiag.pod on defined %hash
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From:
Kevin Ryde
Date:
July 24, 2011 20:26
Subject:
[perl #95538] perldiag.pod on defined %hash
Message ID:
rt-3.6.HEAD-7815-1311552340-604.95538-75-0@perl.org
# New Ticket Created by Kevin Ryde
# Please include the string: [perl #95538]
# in the subject line of all future correspondence about this issue.
# <URL: https://rt.perl.org:443/rt3/Ticket/Display.html?id=95538 >
I found the perldiag.pod description of item "defined(%hash) is
deprecated" unclear.
At first I thought it was threatening another incompatible change, but
if I'm not mistaken it's merely that defined %hash has only ever been a
check for non-empty, which may not be what you intended. If so then
perhaps a wording like the following could make it clearer,
(D deprecated) C<defined()> is not usually useful on hashes, it merely
checks for non-empty, similar to a hash in boolean context (see
L<perldata>). If a non-empty check is what you want then just use
if (%hash) {
# not empty
}
If you had C<defined(%Foo::Bar::QUUX)> to check whether such a package
variable exists, then it has never actually done that, but instead
creates the hash if necessary (autovivification) then tests for
non-empty. If you really want to check existence of a package variable
then look at the glob slot with C<defined *Foo::Bar::QUUX{HASH}> (see
L<perlref>).
[Please do not change anything below this line]
-----------------------------------------------------------------
---
Flags:
category=library
severity=medium
module=Math::BigRat
---
Site configuration information for perl 5.12.4:
Configured by Debian Project at Tue Jun 28 22:20:03 UTC 2011.
Summary of my perl5 (revision 5 version 12 subversion 4) configuration:
Derived from:
Platform:
osname=linux, osvers=2.6.32-5-686, archname=i486-linux-gnu-thread-multi-64int
uname='linux callisto 2.6.32-5-686 #1 smp mon jun 13 04:13:06 utc 2011 i686 gnulinux '
config_args='-Dusethreads -Duselargefiles -Dccflags=-DDEBIAN -Dcccdlflags=-fPIC -Darchname=i486-linux-gnu -Dprefix=/usr -Dprivlib=/usr/share/perl/5.12 -Darchlib=/usr/lib/perl/5.12 -Dvendorprefix=/usr -Dvendorlib=/usr/share/perl5 -Dvendorarch=/usr/lib/perl5 -Dsiteprefix=/usr/local -Dsitelib=/usr/local/share/perl/5.12.4 -Dsitearch=/usr/local/lib/perl/5.12.4 -Dman1dir=/usr/share/man/man1 -Dman3dir=/usr/share/man/man3 -Dsiteman1dir=/usr/local/man/man1 -Dsiteman3dir=/usr/local/man/man3 -Duse64bitint -Dman1ext=1 -Dman3ext=3perl -Dpager=/usr/bin/sensible-pager -Uafs -Ud_csh -Ud_ualarm -Uusesfio -Uusenm -Ui_libutil -DDEBUGGING=-g -Doptimize=-O2 -Duseshrplib -Dlibperl=libperl.so.5.12.4 -des'
hint=recommended, useposix=true, d_sigaction=define
useithreads=define, usemultiplicity=define
useperlio=define, d_sfio=undef, uselargefiles=define, usesocks=undef
use64bitint=define, use64bitall=undef, uselongdouble=undef
usemymalloc=n, bincompat5005=undef
Compiler:
cc='cc', ccflags ='-D_REENTRANT -D_GNU_SOURCE -DDEBIAN -fno-strict-aliasing -pipe -fstack-protector -I/usr/local/include -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64',
optimize='-O2 -g',
cppflags='-D_REENTRANT -D_GNU_SOURCE -DDEBIAN -fno-strict-aliasing -pipe -fstack-protector -I/usr/local/include'
ccversion='', gccversion='4.6.1', gccosandvers=''
intsize=4, longsize=4, ptrsize=4, doublesize=8, byteorder=12345678
d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=12
ivtype='long long', ivsize=8, nvtype='double', nvsize=8, Off_t='off_t', lseeksize=8
alignbytes=4, prototype=define
Linker and Libraries:
ld='cc', ldflags =' -fstack-protector -L/usr/local/lib'
libpth=/usr/local/lib /lib /usr/lib /usr/lib/i386-linux-gnu /usr/lib64
libs=-lgdbm -lgdbm_compat -ldb -ldl -lm -lpthread -lc -lcrypt
perllibs=-ldl -lm -lpthread -lc -lcrypt
libc=, so=so, useshrplib=true, libperl=libperl.so.5.12.4
gnulibc_version='2.13'
Dynamic Linking:
dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-Wl,-E'
cccdlflags='-fPIC', lddlflags='-shared -O2 -g -L/usr/local/lib -fstack-protector'
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