From: Roderick Schertler <roderick@gate.net>
Date: Wed, 8 Jan 1997 03:55:33 +0000 (-0500)
Subject: Misc. doc patches missing in _20
X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=commitdiff_plain;h=b88f04ff2985d0899964b90ae56789d88f6b353e;p=p5sagit%2Fp5-mst-13.2.git

Misc. doc patches missing in _20

Subject: doc patches missing in _20

Here are a couple of the doc patches I sent to the list which didn't get
into _20.  The first looks like an oversight (a related hunk got in),
but perhaps the second was left out intentionally, in anticipation of
changes in signal restart handling?

These are re-diffed against _20.

p5p-msgid: <102.852695733@eeyore.ibcinc.com>
---

diff --git a/pod/perlsub.pod b/pod/perlsub.pod
index bd3eb18..2d3e666 100644
--- a/pod/perlsub.pod
+++ b/pod/perlsub.pod
@@ -754,6 +754,32 @@ starts scribbling on your @_ parameter list.
 This is all very powerful, of course, and should be used only in moderation
 to make the world a better place.  
 
+=head2 Constant Functions
+
+Functions with a prototype of C<()> are potential candidates for
+inlining.  If the result after optimization and constant folding is a
+constant then it will be used in place of calls to the function.
+
+All of the following functions would be inlined.
+
+    sub PI ()		{ 3.14159 }
+    sub ST_DEV ()	{ 0 }
+    sub ST_INO ()	{ 1 }
+
+    sub FLAG_FOO ()	{ 1 << 8 }
+    sub FLAG_BAR ()	{ 1 << 9 }
+    sub FLAG_MASK ()	{ FLAG_FOO | FLAG_BAR }
+    
+    sub OPT_BAZ ()	{ 1 }
+    sub BAZ_VAL () {
+	if (OPT_BAZ) {
+	    return 23;
+	}
+	else {
+	    return 42;
+	}
+    }
+
 If you redefine a subroutine which was eligible for inlining you'll get
 a mandatory warning.  (You can use this warning to tell whether or not a
 particular subroutine is considered constant.)  The warning is
diff --git a/pod/perlvar.pod b/pod/perlvar.pod
index a049e9d..de9bd22 100644
--- a/pod/perlvar.pod
+++ b/pod/perlvar.pod
@@ -698,6 +698,22 @@ sometimes it's a string representing the function, and sometimes it's
 going to call the subroutine call right then and there!  Best to be sure
 and quote it or take a reference to it.  *Plumber works too.  See L<perlsub>.
 
+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 it 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: $!\n";
+
+See L<POSIX>.
+
 Certain internal hooks can be also set using the %SIG hash.  The
 routine indicated by C<$SIG{__WARN__}> is called when a warning message is
 about to be printed.  The warning message is passed as the first