X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=pod%2Fperlvar.pod;h=8fc74417d74bc45c46868f61e04528f30946ea85;hb=6d3b25aa06c9837fbb97c3791369b6d8990787c7;hp=43e14686919838831278f35c0244914588f9ca5e;hpb=dda345b7d3b1ba770b2bb4401e3983c755467731;p=p5sagit%2Fp5-mst-13.2.git diff --git a/pod/perlvar.pod b/pod/perlvar.pod index 43e1468..8fc7441 100644 --- a/pod/perlvar.pod +++ b/pod/perlvar.pod @@ -177,6 +177,11 @@ test. Outside a C test, this will not happen. =back +As C<$_> is a global variable, this may lead in some cases to unwanted +side-effects. As of perl 5.9.1, you can now use a lexical version of +C<$_> by declaring it in a file or in a block with C. Moreover, +declaring C restores the global C<$_> in the current scope. + (Mnemonic: underline is understood in certain operations.) =back @@ -189,10 +194,9 @@ test. Outside a C test, this will not happen. Special package variables when using sort(), see L. Because of this specialness $a and $b don't need to be declared -(using local(), use vars, or our()) even when using the strict -vars pragma. Don't lexicalize them with C or C -if you want to be able to use them in the sort() comparison block -or function. +(using use vars, or our()) even when using the C pragma. +Don't lexicalize them with C or C if you want to be +able to use them in the sort() comparison block or function. =back @@ -471,8 +475,6 @@ taken for something more important.) Consider using "real" multidimensional arrays as described in L. -=item $OFMT - =item $# The output format for printed numbers. This variable is a half-hearted @@ -675,7 +677,7 @@ In the above I stands for anything: zero, non-zero, C. A successful system or library call does B set the variable to zero. -If used an a string, yields the corresponding system error string. +If used as a string, yields the corresponding system error string. You can assign a number to C<$!> to set I if, for instance, you want C<"$!"> to return the string for error I, or you want to set the exit value for the die() operator. (Mnemonic: What just @@ -854,7 +856,8 @@ 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. +length of the argument area, no matter what you do (this is the case +for example with Linux 2.2). 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"> may @@ -1077,6 +1080,10 @@ Provide informative "file" names for evals based on the place they were compiled Provide informative names to anonymous subroutines based on the place they were compiled. +=item 0x400 + +Debug assertion subroutines enter/exit. + =back Some bits may be relevant at compile-time only, some at @@ -1331,24 +1338,11 @@ Be sure not to use a bareword as the name of a signal handler, lest you inadvertently call it. If your system has the sigaction() function then signal handlers are -installed using it. This means you get reliable signal handling. If -your system has the SA_RESTART flag it is used when signals handlers are -installed. This means that system calls for which restarting is supported -continue rather than returning when a signal arrives. If you want your -system calls to be interrupted by signal delivery then do something like -this: - - use POSIX ':signal_h'; - - my $alarm = 0; - sigaction SIGALRM, new POSIX::SigAction sub { $alarm = 1 } - or die "Error setting SIGALRM handler: $!\n"; - -See L. +installed using it. This means you get reliable signal handling. -The delivery policy of signals changed in Perl 5.8.0 from immediate -(also known as "unsafe") to deferred, also known as "safe signals". -See L for more information. +The default delivery policy of signals changed in Perl 5.8.0 from +immediate (also known as "unsafe") to deferred, also known as +"safe signals". See L for more information. Certain internal hooks can be also set using the %SIG hash. The routine indicated by C<$SIG{__WARN__}> is called when a warning message is