perlbug-followup at perl
Jul 3, 2012, 3:01 AM
Post #1 of 5
(61 views)
Permalink
|
|
[perl #113962] /r modifier on substitutions - variant returning undef if no match
|
|
# New Ticket Created by "Ed Avis"
# Please include the string: [perl #113962]
# in the subject line of all future correspondence about this issue.
# <URL: https://rt.perl.org:443/rt3/Ticket/Display.html?id=113962 >
This is a bug report for perl from eda [at] waniasset,
generated with the help of perlbug 1.39 running under perl 5.14.2.
-----------------------------------------------------------------
[Please describe your issue here]
The new /r flag introduced for the s/// and tr/// operators in perl
5.14 is useful, but not as useful as it could be. Careful programming
will often check that the substitution matched:
my $old = 'cat';
(my $new = $old) =~ s/cat/dog/ or die;
While the intention of /r is to simplify the use of substitution,
partly in idioms like the above and partly inside map {}, it is hard
to use it if you wanted to check that the substitution succeeded.
The code above cannot be straightforwardly rewritten using /r and
nor can you straightforwardly map {} over an array performing a
substitution on each item and checking it succeeded.
I suggest a variant which performs the substitution and returns
either the new string, or undef if no match. Suppose the modifier
/R is used for this purpose. Then
my $new = $old =~ s/cat/dog/R // die;
my @new = map { s/cat/dog/R // die } @old;
[Please do not change anything below this line]
-----------------------------------------------------------------
---
Flags:
category=core
severity=wishlist
---
This perlbug was built using Perl 5.14.2 in the Fedora build system.
It is being executed now by Perl 5.14.2 - Wed May 30 15:40:46 UTC 2012.
Site configuration information for perl 5.14.2:
Configured by Red Hat, Inc. at Wed May 30 15:40:46 UTC 2012.
Summary of my perl5 (revision 5 version 14 subversion 2) configuration:
Platform:
osname=linux, osvers=2.6.32-220.4.1.el6.x86_64,
archname=x86_64-linux-thread-multi
uname='linux x86-17.phx2.fedoraproject.org 2.6.32-220.4.1.el6.x86_64
#1 smp thu jan 19 14:50:54 est 2012 x86_64 x86_64 x86_64 gnulinux '
config_args='-des -Doptimize=-O2 -g -pipe -Wall
-Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector
--param=ssp-buffer-size=4 -m64 -mtune=generic
-Dccdlflags=-Wl,--enable-new-dtags -DDEBUGGING=-g -Dversion=5.14.2
-Dmyhostname=localhost -Dperladmin=root [at] localhos -Dcc=gcc -Dcf_by=Red
Hat, Inc. -Dprefix=/usr -Dvendorprefix=/usr -Dsiteprefix=/usr/local
-Dsitelib=/usr/local/share/perl5 -Dsitearch=/usr/local/lib64/perl5
-Dprivlib=/usr/share/perl5 -Dvendorlib=/usr/share/perl5/vendor_perl
-Darchlib=/usr/lib64/perl5 -Dvendorarch=/usr/lib64/perl5/vendor_perl
-Darchname=x86_64-linux-thread-multi -Dlibpth=/usr/local/lib64 /lib64
/usr/lib64 -Duseshrplib -Dusethreads -Duseithreads
-Dusedtrace=/usr/bin/dtrace -Duselargefiles -Dd_semctl_semun -Di_db
-Ui_ndbm -Di_gdbm -Di_shadow -Di_syslog -Dman3ext=3pm -Duseperlio
-Dinstallusrbinperl=n -Ubincompat5005 -Uversiononly
-Dpager=/usr/bin/less -isr -Dd_gethostent_r_proto -Ud_endhostent_r_proto
-Ud_sethostent_r_proto -Ud_endprotoent_r_proto -Ud_setprotoent_r_proto
-Ud_endservent_r_proto -Ud_setservent_r_proto -Dscriptdir=/usr/bin'
hint=recommended, useposix=true, d_sigaction=define
useithreads=define, usemultiplicity=define
useperlio=define, d_sfio=undef, uselargefiles=define, usesocks=undef
use64bitint=define, use64bitall=define, uselongdouble=undef
usemymalloc=n, bincompat5005=undef
Compiler:
cc='gcc', ccflags ='-D_REENTRANT -D_GNU_SOURCE -fno-strict-aliasing
-pipe -fstack-protector -I/usr/local/include -D_LARGEFILE_SOURCE
-D_FILE_OFFSET_BITS=64',
optimize='-O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions
-fstack-protector --param=ssp-buffer-size=4 -m64 -mtune=generic',
cppflags='-D_REENTRANT -D_GNU_SOURCE -fno-strict-aliasing -pipe
-fstack-protector -I/usr/local/include'
ccversion='', gccversion='4.6.3 20120306 (Red Hat 4.6.3-2)',
gccosandvers=''
intsize=4, longsize=8, ptrsize=8, doublesize=8, byteorder=12345678
d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=16
ivtype='long', ivsize=8, nvtype='double', nvsize=8, Off_t='off_t',
lseeksize=8
alignbytes=8, prototype=define
Linker and Libraries:
ld='gcc', ldflags =' -fstack-protector'
libpth=/usr/local/lib64 /lib64 /usr/lib64
libs=-lresolv -lnsl -lgdbm -ldb -ldl -lm -lcrypt -lutil -lpthread
-lc -lgdbm_compat
perllibs=-lresolv -lnsl -ldl -lm -lcrypt -lutil -lpthread -lc
libc=, so=so, useshrplib=true, libperl=libperl.so
gnulibc_version='2.14.90'
Dynamic Linking:
dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef,
ccdlflags='-Wl,--enable-new-dtags -Wl,-rpath,/usr/lib64/perl5/CORE'
cccdlflags='-fPIC', lddlflags='-shared -O2 -g -pipe -Wall
-Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector
--param=ssp-buffer-size=4 -m64 -mtune=generic'
Locally applied patches:
---
@INC for perl 5.14.2:
/home/eda/lib/perl5//x86_64-linux-thread-multi
/home/eda/lib/perl5/
/usr/local/lib64/perl5
/usr/local/share/perl5
/usr/lib64/perl5/vendor_perl
/usr/share/perl5/vendor_perl
/usr/lib64/perl5
/usr/share/perl5
.
---
Environment for perl 5.14.2:
HOME=/home/eda
LANG=en_GB.UTF-8
LANGUAGE (unset)
LC_COLLATE=C
LC_CTYPE=en_GB.UTF-8
LC_MESSAGES=en_GB.UTF-8
LC_MONETARY=en_GB.UTF-8
LC_NUMERIC=en_GB.UTF-8
LC_TIME=en_GB.UTF-8
LD_LIBRARY_PATH (unset)
LOGDIR (unset)
PATH=/home/eda/bin:/home/eda/bin:/usr/local/bin:/bin:/usr/bin:/sbin:/usr
/sbin:/sbin:/usr/sbin
PERL5LIB=/home/eda/lib/perl5/
PERL_BADLANG (unset)
SHELL=/bin/bash
______________________________________________________________________
This email has been scanned by the Symantec Email Security.cloud service.
For more information please visit http://www.symanteccloud.com
______________________________________________________________________
|
