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[perl #116773] Documentation of $ in perlre

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From:
Rob Dixon
Date:
February 15, 2013 21:59
Subject:
[perl #116773] Documentation of $ in perlre
Message ID:
rt-3.6.HEAD-27190-1360935939-1202.116773-75-0@perl.org
# New Ticket Created by  Rob Dixon 
# Please include the string:  [perl #116773]
# in the subject line of all future correspondence about this issue. 
# <URL: https://rt.perl.org:443/rt3/Ticket/Display.html?id=116773 >




This is a bug report for perl from rob.dixon@gmx.com,
generated with the help of perlbug 1.39 running under perl 5.16.2.


-----------------------------------------------------------------

I have been working with a regular expression that uses `$` with the
`/m` modifier, and have relaised that I was misunderstanding how `$`
works. The problem is the line

     $        Match the end of the line (or before newline at the end)

The way I read that is that `$` matches both before and after a
newline, whereas what this actually means is

    Match the end of the _string_ (or before a newline at the end of the 
_string_)

This makes no difference without the `/m` modifier, but with it I was
expecting `$` to match twice for each line. After all that is what the
documentation says!

A _line_ is something very specific, and it is fair to think of it as
a thing that is terminated by a newline character. Because regular
expressions allow for multi-line strings I feel this should be changed.



-----------------------------------------------------------------
---
Flags:
     category=docs
     severity=medium
---
Site configuration information for perl 5.16.2:

Configured by strawberry-perl at Fri Nov  2 00:34:53 2012.

Summary of my perl5 (revision 5 version 16 subversion 2) configuration:

   Platform:
     osname=MSWin32, osvers=4.0, archname=MSWin32-x86-multi-thread
     uname='Win32 strawberry-perl 5.16.2.1 #1 Fri Nov  2 00:33:54 2012 i386'
     config_args='undef'
     hint=recommended, useposix=true, d_sigaction=undef
     useithreads=define, usemultiplicity=define
     useperlio=define, d_sfio=undef, uselargefiles=define, usesocks=undef
     use64bitint=undef, use64bitall=undef, uselongdouble=undef
     usemymalloc=n, bincompat5005=undef
   Compiler:
     cc='gcc', ccflags =' -s -O2 -DWIN32  -DPERL_TEXTMODE_SCRIPTS 
-DPERL_IMPLICIT_CONTEXT -DPERL_IMPLICIT_SYS -fno-strict-aliasing 
-mms-bitfields',
     optimize='-s -O2',
     cppflags='-DWIN32'
     ccversion='', gccversion='4.6.3', gccosandvers=''
     intsize=4, longsize=4, ptrsize=4, doublesize=8, byteorder=1234
     d_longlong=undef, longlongsize=8, d_longdbl=define, longdblsize=12
     ivtype='long', ivsize=4, nvtype='double', nvsize=8, Off_t='long 
long', lseeksize=8
     alignbytes=8, prototype=define
   Linker and Libraries:
     ld='g++', ldflags ='-s -L"C:\strawberry\perl\lib\CORE" 
-L"C:\strawberry\c\lib"'
     libpth=C:\strawberry\c\lib C:\strawberry\c\i686-w64-mingw32\lib
     libs=-lmoldname -lkernel32 -luser32 -lgdi32 -lwinspool -lcomdlg32 
-ladvapi32 -lshell32 -lole32 -loleaut32 -lnetapi32 -luuid -lws2_32 -lmpr 
-lwinmm -lversion -lodbc32 -lodbccp32 -lcomctl32
     perllibs=-lmoldname -lkernel32 -luser32 -lgdi32 -lwinspool 
-lcomdlg32 -ladvapi32 -lshell32 -lole32 -loleaut32 -lnetapi32 -luuid 
-lws2_32 -lmpr -lwinmm -lversion -lodbc32 -lodbccp32 -lcomctl32
     libc=, so=dll, useshrplib=true, libperl=libperl516.a
     gnulibc_version=''
   Dynamic Linking:
     dlsrc=dl_win32.xs, dlext=dll, d_dlsymun=undef, ccdlflags=' '
     cccdlflags=' ', lddlflags='-mdll -s -L"C:\strawberry\perl\lib\CORE" 
-L"C:\strawberry\c\lib"'

Locally applied patches:


---
@INC for perl 5.16.2:
     C:/strawberry/perl/site/lib/MSWin32-x86-multi-thread
     C:/strawberry/perl/site/lib
     C:/strawberry/perl/vendor/lib
     C:/strawberry/perl/lib
     .

---
Environment for perl 5.16.2:
     HOME (unset)
     LANG (unset)
     LANGUAGE (unset)
     LD_LIBRARY_PATH (unset)
     LOGDIR (unset)
     PATH=C:\Program Files (x86)\NVIDIA 
Corporation\PhysX\Common;C:\Program Files (x86)\PC Connectivity 
Solution\;C:\Program Files\Common Files\Microsoft Shared\Windows 
Live;C:\Program Files 
(x86)\PHP\;C:\Windows\system32;C:\Windows;C:\Windows\System32\Wbem;C:\Windows\System32\WindowsPowerShell\v1.0\;C:\Program 
Files\jEdit;C:\usr\local\ppt\bin;C:\Program Files 
(x86)\GnuWin32\bin;C:\Program Files (x86)\Smart 
Projects\IsoBuster;C:\Program Files (x86)\Oracle\Berkeley DB 11gR2 
5.3.15\bin;C:\Program Files (x86)\Git\cmd;C:\Program Files 
(x86)\Calibre2\;C:\Program Files (x86)\Bazaar;C:\Program Files 
(x86)\Lua\5.1;C:\Program Files 
(x86)\Lua\5.1\clibs;C:\strawberry\c\bin;C:\strawberry\perl\site\bin;C:\strawberry\perl\bin;C:\Program 
Files\TortoiseSVN\bin;C:\MediaInfoCLI;C:\Program Files\WinRAR;C:\Program 
Files\Common Files\Microsoft Shared\Windows Live;C:\Program Files 
(x86)\Common Files\Hackety Hack\0.r1529\..;C:\Program Files (x86)\IDM 
Computer Solutions\UltraCompare\;C:\ffmpeg\bin;C:\Program Files 
(x86)\Serviio\lib;C:\Program Files (x86)\Microsoft Visual Studio 
10.0\VC\bin\x86_amd64;C:\Program Files (x86)\Microsoft Visual Studio 
10.0\VC\bin\amd64;C:\SWIG;C:\MinGW\bin;C:\MinGW\MSYS\1.0\bin;C:\Python27;C:\Curl;C:\pkg-config\bin;C:\glib\bin;C:\gettext-runtime\bin;C:\Program 
Files (x86)\IDM Computer Solutions\UltraEdit\;C:\LuaRocks\2.0
     PERL_BADLANG (unset)
     SHELL (unset)


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