X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=pod%2Fperlvar.pod;h=43e14686919838831278f35c0244914588f9ca5e;hb=dda345b7d3b1ba770b2bb4401e3983c755467731;hp=a4e889562ea515755f9fe0be55a0195a933e5a26;hpb=5b88253beb15ba0b9f2b2ef15037de4950b82796;p=p5sagit%2Fp5-mst-13.2.git diff --git a/pod/perlvar.pod b/pod/perlvar.pod index a4e8895..43e1468 100644 --- a/pod/perlvar.pod +++ b/pod/perlvar.pod @@ -294,26 +294,6 @@ past where $2 ends, and so on. You can use C<$#+> to determine how many subgroups were in the last successful match. See the examples given for the C<@-> variable. -=item $MULTILINE_MATCHING - -=item $* - -Set to a non-zero integer value to do multi-line matching within a -string, 0 (or undefined) to tell Perl that it can assume that strings -contain a single line, for the purpose of optimizing pattern matches. -Pattern matches on strings containing multiple newlines can produce -confusing results when C<$*> is 0 or undefined. Default is undefined. -(Mnemonic: * matches multiple things.) This variable influences the -interpretation of only C<^> and C<$>. A literal newline can be searched -for even when C<$* == 0>. - -Use of C<$*> is deprecated in modern Perl, supplanted by -the C and C modifiers on pattern matching. - -Assigning a non-numerical value to C<$*> triggers a warning (and makes -C<$*> act if C<$* == 0>), while assigning a numerical value to C<$*> -makes that an implicit C is applied on the value. - =item HANDLE->input_line_number(EXPR) =item $INPUT_LINE_NUMBER @@ -858,20 +838,35 @@ and C<$)> can be swapped only on machines supporting setregid(). =item $0 -Contains the name of the program being executed. On some operating -systems assigning to C<$0> modifies the argument area that the B -program sees. This is more useful as a way of indicating the current -program state than it is for hiding the program you're running. -(Mnemonic: same as B and B.) +Contains the name of the program being executed. + +On some (read: not all) operating systems assigning to C<$0> modifies +the argument area that the C program sees. On some platforms you +may have to use special C options or a different C to see the +changes. Modifying the $0 is more useful as a way of indicating the +current program state than it is for hiding the program you're +running. (Mnemonic: same as B and B.) + +Note that there are platform specific limitations on the the maximum +length of C<$0>. In the most extreme case it may be limited to the +space occupied by the original C<$0>. + +In some platforms there may be arbitrary amount of padding, for +example space characters, after the modified name as shown by C. +In some platforms this padding may extend all the way to the original +length of the argument area, no matter what you do. Note for BSD users: setting C<$0> does not completely remove "perl" -from the ps(1) output. For example, setting C<$0> to C<"foobar"> will -result in C<"perl: foobar (perl)">. This is an operating system -feature. +from the ps(1) output. For example, setting C<$0> to C<"foobar"> may +result in C<"perl: foobar (perl)"> (whether both the C<"perl: "> prefix +and the " (perl)" suffix are shown depends on your exact BSD variant +and version). This is an operating system feature, Perl cannot help it. In multithreaded scripts Perl coordinates the threads so that any thread may modify its copy of the C<$0> and the change becomes visible -to ps(1) (assuming the operating system plays along). +to ps(1) (assuming the operating system plays along). Note that the +the view of C<$0> the other threads have will not change since they +have their own copies of it. =item $[ @@ -883,8 +878,14 @@ subscripting and when evaluating the index() and substr() functions. As of release 5 of Perl, assignment to C<$[> is treated as a compiler directive, and cannot influence the behavior of any other file. +(That's why you can only assign compile-time constants to it.) Its use is highly discouraged. +Note that, unlike other compile-time directives (such as L), +assignment to $[ can be seen from outer lexical scopes in the same file. +However, you can use local() on it to strictly bound its value to a +lexical block. + =item $] The version + patchlevel / 1000 of the Perl interpreter. This variable @@ -916,7 +917,8 @@ C<$^C = 1> is similar to calling C. =item $^D The current value of the debugging flags. (Mnemonic: value of B<-D> -switch.) +switch.) May be read or set. Like its command-line equivalent, you can use +numeric or symbolic values, eg C<$^D = 10> or C<$^D = "st">. =item $SYSTEM_FD_MAX @@ -1117,9 +1119,10 @@ B<-t> or B<-TU>). This variable is read-only. =item ${^UNICODE} -Reflects certain Unicode settings of Perl. See L for more -information about the possible values. This variable is set during -Perl startup and thereafter read-only. +Reflects certain Unicode settings of Perl. See L +documentation for the C<-C> switch for more information about +the possible values. This variable is set during Perl startup +and is thereafter read-only. =item $PERL_VERSION @@ -1343,6 +1346,10 @@ this: See L. +The delivery policy of signals changed in Perl 5.8.0 from immediate +(also known as "unsafe") to deferred, also known as "safe signals". +See L for more information. + Certain internal hooks can be also set using the %SIG hash. The routine indicated by C<$SIG{__WARN__}> is called when a warning message is about to be printed. The warning message is passed as the first