p5pRT
commented
23 years ago From @mjdominus
use Mod;
$z = 1; --------------------------------base.pl
--------------------------------Mod.pm package Mod; use warnings;
1; --------------------------------Mod.pm
When I run this with 5.6.0\, I get:
% perl base.pl Name "main::z" used only once: possible typo at base.pl line 5.
The 'use warnings' directive\, which was supposed to have been lexically scoped to affect only Mod.pm\, has leaked out because Perl issued a warning for the $z variable.
This is a big problem. Here is why:
I have Perl programs that run every minute from a cron job. I just upgraded DB_File. The new version of DB_File says 'use warnings'. Suddenly I am getting an email a minute from the cron job warning me about 'used only once'. Formerly\, the cron job was silent.
I thought that this was exactly the kind of action-at-a-distance
problem that 'lexical warnings' was supposed to address.
The documentation in warnings.pm says:
the pragma setting will not leak across files (via `use'\, `require' or `do').
If it doesn't keep this promise\, then there is little benefit to be had over using $^W.
Hildo\, you and Phil told me that you folks had had a lot of trouble with this same sort of problem in the past\, and that the changed warning behavior is exactly the reason why 5.004 is still the default at MSDW. I have copied you to let you know that upgrading a module may cause the same sorts of problems.
Paul\, your email address is not in the manual.
Summary of my perl5 (revision 5.0 version 6 subversion 0) configuration: Platform: osname=linux\, osvers=2.2.16\, archname=i586-linux uname='linux plover 2.2.16 #97 fri jun 16 19:45:30 pdt 2000 i586 unknown ' config_args='-Doptimize=-g -des' hint=recommended\, useposix=true\, d_sigaction=define usethreads=undef use5005threads=undef useithreads=undef usemultiplicity=undef useperlio=undef d_sfio=undef uselargefiles=define use64bitint=undef use64bitall=undef uselongdouble=undef usesocks=undef Compiler: cc='cc'\, optimize='-g'\, gccversion=egcs-2.91.66 19990314/Linux (egcs-1.1.2 release) cppflags='-DDEBUGGING -fno-strict-aliasing -I/usr/local/include' ccflags ='-DDEBUGGING -fno-strict-aliasing -I/usr/local/include -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64' stdchar='char'\, d_stdstdio=define\, usevfork=false intsize=4\, longsize=4\, ptrsize=4\, doublesize=8 d_longlong=define\, longlongsize=8\, d_longdbl=define\, longdblsize=12 ivtype='long'\, ivsize=4\, nvtype='double'\, nvsize=8\, Off_t='off_t'\, lseeksize=8 alignbytes=4\, usemymalloc=n\, prototype=define Linker and Libraries: ld='cc'\, ldflags =' -L/usr/local/lib' libpth=/usr/local/lib /lib /usr/lib libs=-lnsl -lndbm -lgdbm -ldb -ldl -lm -lc -lposix -lcrypt libc=/lib/libc-2.1.3.so\, so=so\, useshrplib=false\, libperl=libperl.a Dynamic Linking: dlsrc=dl_dlopen.xs\, dlext=so\, d_dlsymun=undef\, ccdlflags='-rdynamic' cccdlflags='-fpic'\, lddlflags='-shared -L/usr/local/lib'
Characteristics of this binary (from libperl): Compile-time options: DEBUGGING USE_LARGE_FILES Built under linux Compiled at Sep 20 2000 15:38:35 @INC: /usr/local/lib/perl5/5.6.0/i586-linux /usr/local/lib/perl5/5.6.0 /usr/local/lib/perl5/site_perl/5.6.0/i586-linux /usr/local/lib/perl5/site_perl/5.6.0 /usr/local/lib/perl5/site_perl .
Migrated from rt.perl.org#6302 (status was 'resolved')
Searchable as RT6302$