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authorPerl 5 Porters <perl5-porters@africa.nicoh.com>1997-03-09 11:57:19 +1200
committerChip Salzenberg <chip@atlantic.net>1997-03-09 11:57:19 +1200
commit68dc074516a6859e3424b48d1647bcb08b1a1a7d (patch)
tree125011c6d8e4a04727ff97166dc19199809958e4 /pod/perlre.pod
parent699e6cd4da8c333ef83554732e73ab6734463b5d (diff)
downloadperl-68dc074516a6859e3424b48d1647bcb08b1a1a7d.tar.gz
[inseparable changes from match from perl-5.003_93 to perl-5.003_94]
BUILD PROCESS Subject: Don't use db 2.x, we're not yet ready for it From: Paul Marquess <pmarquess@bfsec.bt.co.uk> Files: Configure Subject: Warn if #! command is longer than 32 chars From: Chip Salzenberg <chip@perl.com> Files: Configure Subject: patches re perl -wc install{perl,man} Date: Tue, 11 Mar 97 13:13:16 GMT From: Robin Barker <rmb1@cise.npl.co.uk> Files: installman installperl I got the new installhtml from CPAN (TOMC/scripts/pod2html-v2.0beta.shar.gz) I had problems getting the system call to splitpod at line 376 to work. 1. splitroot was not being found 2. splitroot was not finding its library 3. I changed htmlroot to podroot at line 175 to match the documentation. p5p-msgid: 3180.9703270906@tempest.cise.npl.co.uk private-msgid: 21544.9703111313@tempest.cise.npl.co.uk Subject: 3_93 doesn't install pods Date: Sun, 16 Mar 1997 02:21:35 -0500 From: Spider Boardman <spider@orb.nashua.nh.us> Files: installperl Msg-ID: 199703160721.CAA08339@Orb.Nashua.NH.US (applied based on p5p patch as commit 43506a616735d616e03d277d64fbae1e864024bf) Subject: When installing, use File::Copy instead of `cp` From: Chip Salzenberg <chip@perl.com> Files: installperl Subject: Make hint files' warnings more visible Date: Thu, 20 Mar 1997 23:18:03 +0100 (MET) From: Hallvard B Furuseth <h.b.furuseth@usit.uio.no> Files: hints/3b1.sh hints/apollo.sh hints/cxux.sh hints/dcosx.sh hints/dgux.sh hints/esix4.sh hints/freebsd.sh hints/hpux.sh hints/irix_4.sh hints/mips.sh hints/next_3_0.sh hints/os2.sh hints/qnx.sh hints/sco_2_3_3.sh hints/sco_2_3_4.sh hints/solaris_2.sh hints/ultrix_4.sh hints/utekv.sh private-msgid: 199703202218.XAA09041@bombur2.uio.no CORE LANGUAGE CHANGES Subject: Defer creation of array and hash elements as parameters From: Chip Salzenberg <chip@perl.com> Files: dump.c global.sym mg.c op.c op.h perl.h pp.c pp_hot.c proto.h sv.c Subject: New special literal: __PACKAGE__ From: Chip Salzenberg <chip@perl.com> Files: keywords.pl pod/perldata.pod toke.c Subject: Abort compilation at C<BEGIN{}> or C<use> after errors From: Chip Salzenberg <chip@perl.com> Files: op.c pod/perldiag.pod t/pragma/subs.t Subject: allow C<substr 'hello', -10> Date: Mon, 10 Mar 1997 15:55:44 -0800 From: David Dyck <dcd@tc.fluke.com> Files: pp.c Msg-ID: 97Mar10.155517pst.35716-2@gateway.fluke.com (applied based on p5p patch as commit 77f720bf92f3d0100352416caeedd57936807ff2) Subject: Regularize C<x % y>, esp. when y is negative From: Chip Salzenberg <chip@perl.com> Files: pp.c Subject: Flush before C<flock(FOO, LOCK_UN)> From: Chip Salzenberg <chip@perl.com> Files: pod/perldelta.pod pod/perlfunc.pod pp_sys.c Subject: Close loopholes in prototype mismatch warning From: Chip Salzenberg <chip@perl.com> Files: op.c sv.c toke.c Subject: Warn on C<while ($x = each %y) {}> From: Chip Salzenberg <chip@perl.com> Files: op.c pod/perldiag.pod Subject: Don't warn on C<print $fh func()> From: Chip Salzenberg <chip@perl.com> Files: toke.c CORE PORTABILITY Subject: Don't say 'static var = 1' Date: Sun, 9 Mar 1997 15:19:57 +0200 (EET) From: Jarkko Hietaniemi <jhi@iki.fi> Files: malloc.c private-msgid: 199703091319.PAA24714@alpha.hut.fi Subject: HP/UX hint comments Date: Fri, 21 Mar 1997 15:43:07 -0500 (EST) From: Andy Dougherty <doughera@fractal.phys.lafayette.edu> Files: hints/hpux.sh private-msgid: Pine.SOL.3.95q.970321153918.28770B-100000@fractal.lafayette. Subject: VMS update Date: Tue, 11 Mar 1997 22:00:55 -0500 (EST) From: Charles Bailey <bailey@hmivax.humgen.upenn.edu> Files: lib/ExtUtils/MM_VMS.pm lib/Test/Harness.pm t/op/taint.t utils/perlbug.PL vms/descrip.mms Msg-ID: 1997Mar11.220056.1873182@hmivax.humgen.upenn.edu (applied based on p5p patch as commit 2b5725676da60b49978f38b85bb7f8ee20b4cb55) Subject: vmsish.t and related patches Date: Fri, 21 Mar 1997 01:32:47 -0500 (EST) From: Charles Bailey <bailey@HMIVAX.HUMGEN.UPENN.EDU> Files: MANIFEST perl.h vms/descrip.mms vms/ext/vmsish.t vms/vms.c private-msgid: 01IGQW3IP1KK005VFB@hmivax.humgen.upenn.edu Subject: Win32 update (four patches) From: Gurusamy Sarathy <gsar@engin.umich.edu> Files: MANIFEST README.win32 lib/AutoSplit.pm lib/Cwd.pm lib/ExtUtils/Command.pm lib/ExtUtils/Install.pm lib/ExtUtils/MM_OS2.pm lib/ExtUtils/MM_Unix.pm lib/ExtUtils/MM_Win32.pm lib/ExtUtils/MakeMaker.pm lib/ExtUtils/Mksymlists.pm lib/File/Basename.pm lib/File/Path.pm mg.c t/comp/cpp.t t/comp/script.t t/harness t/io/argv.t t/io/dup.t t/io/fs.t t/io/inplace.t t/lib/filehand.t t/lib/io_dup.t t/lib/io_sel.t t/lib/io_taint.t t/op/closure.t t/op/exec.t t/op/glob.t t/op/goto.t t/op/magic.t t/op/misc.t t/op/rand.t t/op/split.t t/op/stat.t t/op/sysio.t t/op/taint.t t/pragma/strict.t t/pragma/subs.t t/pragma/warning.t util.c win32/* DOCUMENTATION Subject: perlfaq.pod Date: Mon, 17 Mar 1997 16:01:40 -0700 From: Tom Christiansen <tchrist@jhereg.perl.com> Files: MANIFEST pod/Makefile pod/buildtoc pod/perl.pod pod/perlfaq*.pod pod/roffitall private-msgid: 199703172301.QAA12566@jhereg.perl.com Subject: *.pod changes based on the FAQ Date: Mon, 17 Mar 1997 09:50:14 -0700 (MST) From: Nat Torkington <gnat@frii.com> Files: pod/perldata.pod pod/perlfunc.pod pod/perlipc.pod pod/perlop.pod pod/perlre.pod pod/perlrun.pod pod/perlsec.pod pod/perlvar.pod Msg-ID: 199703171650.JAA02655@elara.frii.com (applied based on p5p patch as commit 3c10ad8e31f7d77e71c048b1746912f41cb540f0) Subject: Document that $. is not reset on implicit open From: Chip Salzenberg <chip@perl.com> Files: pod/perldelta.pod Subject: Re: Embedding success with _93 Date: Tue, 11 Mar 1997 17:55:05 -0500 From: Doug MacEachern <dougm@opengroup.org> Files: pod/perldelta.pod Msg-ID: 199703112255.RAA22775@postman.osf.org (applied based on p5p patch as commit 63a6ff3a1dc8d86edb4d8a7ec1548205e32a7114) Subject: Patch to document illegal characters Date: Fri, 14 Mar 1997 09:08:10 -0800 (PST) From: Tom Phoenix <rootbeer@teleport.com> Files: pod/perldiag.pod pod/perltrap.pod private-msgid: Pine.GSO.3.96.970314090558.15346J-100000@kelly.teleport.com Subject: Document trap with //o and closures Date: Mon, 10 Mar 1997 18:08:08 -0500 (EST) From: Charles Bailey <bailey@HMIVAX.HUMGEN.UPENN.EDU> Files: pod/perltrap.pod Msg-ID: 01IGCHWRNSEU00661G@hmivax.humgen.upenn.edu (applied based on p5p patch as commit a54cb1465fdb400848f23705a6f130bb5c34ab70) Subject: Illegal character in input Date: Mon, 10 Mar 1997 15:21:21 -0800 (PST) From: Tom Phoenix <rootbeer@teleport.com> Files: pod/perldiag.pod private-msgid: Pine.GSO.3.95q.970310151512.22489a-100000@kelly.teleport.com Subject: Patch for docs Re: Lost backslash Date: Wed, 19 Mar 1997 07:28:57 -0800 (PST) From: Tom Phoenix <rootbeer@teleport.com> Files: pod/perlop.pod private-msgid: Pine.GSO.3.96.970319071438.24834G-100000@kelly.teleport.com Subject: XSUB's doc fix Date: Mon, 10 Mar 1997 11:42:06 -0500 From: Roderick Schertler <roderick@argon.org> Files: pod/perlcall.pod pod/perlguts.pod pod/perlxstut.pod Msg-ID: 28804.858012126@eeyore.ibcinc.com (applied based on p5p patch as commit 5f43237038ea7a4151d3bf65aeeecd56ceb78a6a) Subject: Document return from do FILE Date: Tue, 18 Mar 1997 14:50:10 +0000 From: "M.J.T. Guy" <mjtg@cus.cam.ac.uk> Files: pod/perlfunc.pod Msg-ID: E0w70DK-0001yJ-00@ursa.cus.cam.ac.uk (applied based on p5p patch as commit ba8d5fb439878113de8abc9b52d2af237d30fb3c) Subject: Document $^M in perlvar Date: Thu, 20 Mar 97 21:08:33 GMT From: Robin Barker <rmb1@cise.npl.co.uk> Files: pod/perlvar.pod private-msgid: 6153.9703202108@tempest.cise.npl.co.uk Subject: typos in pods of 5.003_93 Date: 19 Mar 1997 10:39:38 -0600 From: Jim Meyering <meyering@asic.sc.ti.com> Files: pod/perlfunc.pod pod/perlguts.pod pod/perlre.pod pod/perltoot.pod pod/perlxs.pod Msg-ID: wpgendbzvhx.fsf@asic.sc.ti.com (applied based on p5p patch as commit 76a9873e006cf8f48f57062b2a0dd40b5ed45a95) Subject: Re: Updates to pod punctuations Date: Fri, 14 Mar 1997 17:00:12 -0500 From: Larry W. Virden <lvirden@cas.org> Files: pod/*.pod private-msgid: 9703141700.AA22911@cas.org Subject: clarify example in perlfunc Date: Thu, 20 Mar 1997 19:46:01 +0200 (EET) From: Jarkko Hietaniemi <jhi@iki.fi> Files: pod/perlfunc.pod private-msgid: 199703201746.TAA25195@alpha.hut.fi Subject: Regularize headings in DB_File documentation From: Chip Salzenberg <chip@perl.com> Files: ext/DB_File/DB_File.pm LIBRARY AND EXTENSIONS Subject: New module: autouse.pm Date: Thu, 20 Mar 1997 19:34:30 -0500 (EST) From: Ilya Zakharevich <ilya@math.ohio-state.edu> Files: MANIFEST lib/autouse.pm Msg-ID: 199703210034.TAA13469@monk.mps.ohio-state.edu (applied based on p5p patch as commit 6757905eccb6dd0440ef65e8128a277a20f7d943) Subject: Refresh DB_File to 1.12 Date: Wed, 12 Mar 97 15:51:14 GMT From: Paul Marquess <pmarquess@bfsec.bt.co.uk> Files: ext/DB_File/DB_File.pm ext/DB_File/DB_File.xs Msg-ID: 9703121551.AA07435@claudius.bfsec.bt.co.uk (applied based on p5p patch as commit b3deed9189f963e9994815307931f9084f60d1d9) Subject: In File::Path, some systems can't remove read-only files From: Chip Salzenberg <chip@perl.com> Files: lib/File/Path.pm Subject: Fix bugs revealed by prototype warnings From: Chip Salzenberg <chip@perl.com> Files: ext/Opcode/Opcode.pm lib/ExtUtils/MakeMaker.pm lib/Getopt/Long.pm Subject: Problems with SKIP in makemaker Date: Thu, 20 Mar 1997 23:13:31 -0500 (EST) From: Ilya Zakharevich <ilya@math.ohio-state.edu> Files: lib/ExtUtils/MM_Unix.pm Msg-ID: 199703210413.XAA21601@monk.mps.ohio-state.edu (applied based on p5p patch as commit 970322a2e8024294ada6e8d1a027cb98f1f48ee3) Subject: In Exporter, don't C<require Carp> at file scope From: Chip Salzenberg <chip@perl.com> Files: lib/Exporter.pm Subject: fix for Exporter's $SIG{__WARN__} handler Date: Thu, 13 Mar 1997 18:40:51 -0500 From: Roderick Schertler <roderick@argon.org> Files: lib/Exporter.pm Msg-ID: 2282.858296451@eeyore.ibcinc.com (applied based on p5p patch as commit 2768ea1aeef34f42d096f198fbe629c8374ca429) Subject: Don't try to substr() refs in Carp From: Chip Salzenberg <chip@perl.com> Files: lib/Carp.pm Subject: Re: NUL in die and other messages Date: Fri, 21 Mar 1997 09:58:17 +0000 From: "M.J.T. Guy" <mjtg@cus.cam.ac.uk> Files: lib/Carp.pm Msg-ID: E0w815V-0005xs-00@ursa.cus.cam.ac.uk (applied based on p5p patch as commit 52a267c574cb66c4bc35601dcf148a1d7a3bc557) OTHER CORE CHANGES Subject: Guard against buffer overflow in yyerror() and related funcs From: Chip Salzenberg <chip@perl.com> Files: toke.c Subject: For bin compat, rename calllist() and he_{,delay}free From: Chip Salzenberg <chip@perl.com> Files: global.sym hv.c op.c perl.c pod/perlguts.pod proto.h Subject: Fix C<print> on tied default handle From: Chip Salzenberg <chip@perl.com> Files: pp_hot.c Subject: Fix C<local($a, undef, $b) = (1,2,3)> From: Chip Salzenberg <chip@perl.com> Files: op.c Subject: Improve diagnostic on C<@a++>, C<--%a>, @a =~ s/a/b/ From: Chip Salzenberg <chip@perl.com> Files: pp.c pp_hot.c Subject: Don't warn on C<$x{y} .= "z"> when %x is tied From: Chip Salzenberg <chip@perl.com> Files: pp_hot.c Subject: Eliminate 'unreachable code' warnings From: Chip Salzenberg <chip@perl.com> Files: ext/POSIX/POSIX.xs mg.c pp_ctl.c toke.c Subject: printf format corrections for -DDEBUGGING Date: Wed, 19 Mar 1997 12:42:50 -0500 From: Roderick Schertler <roderick@argon.org> Files: doop.c malloc.c op.c pp_ctl.c regexec.c sv.c x2p/str.c x2p/util.c Msg-ID: 26592.858793370@eeyore.ibcinc.com (applied based on p5p patch as commit e125f273e351a19a92b69d6244af55abbbf0a26d) Subject: Warn about missing -DMULTIPLICITY if likely a problem Date: Wed, 19 Mar 1997 18:45:53 -0500 From: Doug MacEachern <dougm@opengroup.org> Files: perl.c Msg-ID: 199703192345.SAA15070@postman.osf.org (applied based on p5p patch as commit 71aeea1753924e6e19c2461e241e3f7d8a570e90)
Diffstat (limited to 'pod/perlre.pod')
-rw-r--r--pod/perlre.pod22
1 files changed, 17 insertions, 5 deletions
diff --git a/pod/perlre.pod b/pod/perlre.pod
index cb3ce032d0..74a8bd9fd5 100644
--- a/pod/perlre.pod
+++ b/pod/perlre.pod
@@ -9,9 +9,10 @@ description of how to I<use> regular expressions in matching
operations, plus various examples of the same, see C<m//> and C<s///> in
L<perlop>.
-The matching operations can
-have various modifiers, some of which relate to the interpretation of
-the regular expression inside. These are:
+The matching operations can have various modifiers. The modifiers
+which relate to the interpretation of the regular expression inside
+are listed below. For the modifiers that alter the behaviour of the
+operation, see L<perlop/"m//"> and L<perlop/"s//">.
=over 4
@@ -167,7 +168,7 @@ Perl defines the following zero-width assertions:
\G Match only where previous m//g left off
A word boundary (C<\b>) is defined as a spot between two characters that
-has a C<\w> on one side of it and and a C<\W> on the other side of it (in
+has a C<\w> on one side of it and a C<\W> on the other side of it (in
either order), counting the imaginary characters off the beginning and
end of the string as matching a C<\W>. (Within character classes C<\b>
represents backspace rather than a word boundary.) The C<\A> and C<\Z> are
@@ -214,6 +215,17 @@ everything after the matched string. Examples:
$seconds = $3;
}
+Once perl sees that you need one of C<$&>, C<$`> or C<$'> anywhere in
+the program, it has to provide them on each and every pattern match.
+This can slow your program down. The same mechanism that handles
+these provides for the use of $1, $2, etc., so you pay the same price
+for each regexp that contains capturing parentheses. But if you never
+use $&, etc., in your script, then regexps I<without> capturing
+parentheses won't be penalized. So avoid $&, $', and $` if you can,
+but if you can't (and some algorithms really appreciate them), once
+you've used them once, use them at will, because you've already paid
+the price.
+
You will note that all backslashed metacharacters in Perl are
alphanumeric, such as C<\b>, C<\w>, C<\n>. Unlike some other regular expression
languages, there are no backslashed symbols that aren't alphanumeric.
@@ -326,7 +338,7 @@ When the match runs, the first part of the regular expression (C<\b(foo)>)
finds a possible match right at the beginning of the string, and loads up
$1 with "Foo". However, as soon as the matching engine sees that there's
no whitespace following the "Foo" that it had saved in $1, it realizes its
-mistake and starts over again one character after where it had had the
+mistake and starts over again one character after where it had the
tentative match. This time it goes all the way until the next occurrence
of "foo". The complete regular expression matches this time, and you get
the expected output of "table follows foo."