Mention state variables in perldiag. Add switch-related keywords

in the keyword listing section in perlfunc. Add a summary of
C<state> in perlfunc. Fix a typo in the synopsis for C<our>.
Don't say that C<my $_> is illegal in perlsub.

p4raw-id: //depot/perl@28491

1 files changed, 6 insertions, 1 deletions

diff --git a/pod/perldiag.pod b/pod/perldiag.pod
index 93c8767ef3..8228cf9840 100644
--- a/pod/perldiag.pod
+++ b/pod/perldiag.pod
@@ -1422,13 +1422,18 @@ conditional. Some people have exploited this bug to achieve a kind of
 static variable. Since we intend to fix this bug, we don't want people
 relying on this behavior. You can achieve a similar static effect by
 declaring the variable in a separate block outside the function, eg
-    
+
     sub f { my $x if 0; return $x++ }
 
 becomes
 
     { my $x; sub f { return $x++ } }
 
+Beginning with perl 5.9.4, you can also use C<state> variables to
+have lexicals that are initialized only once (see L<feature>):
+
+    sub f { state $x; return $x++ }
+
 =item DESTROY created new reference to dead object '%s'
 
 (F) A DESTROY() method created a new reference to the object which is