Add test for grep() and wantarray

[p5sagit/p5-mst-13.2.git] / pod / perlsub.pod

diff --git a/pod/perlsub.pod b/pod/perlsub.pod
index fa14a7f..347d2f8 100644 (file)
--- a/pod/perlsub.pod
+++ b/pod/perlsub.pod
@@ -608,7 +608,7 @@ If you're planning on generating new filehandles, you could do this:
     sub openit {
        my $name = shift;
        local *FH;
-       return open (FH, $path) ? \*FH : undef;
+       return open (FH, $path) ? *FH : undef;
     } 
 
 Although that will actually produce a small memory leak.  See the bottom
@@ -752,7 +752,35 @@ in @foo.  And the split() gets called in a scalar context and
 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.
+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 new-style calls to the
+function.  Old-style calls (that is, calls made using C<&>) are not
+affected.
+
+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