Clarifications on constants subroutines, based on:

Subject: [perl #27768] [patch] wrong examples in perlsub/"Constant Functions"
From: "padre@elte.hu (via RT)" <perlbug-followup@perl.org>
Message-ID: <rt-3.0.8-27768-82310.5.12766475665209@perl.org>

p4raw-id: //depot/perl@22557

diff --git a/pod/perlsub.pod b/pod/perlsub.pod
index e830130..3619014 100644 (file)
--- a/pod/perlsub.pod
+++ b/pod/perlsub.pod
@@ -1133,7 +1133,17 @@ The following functions would all be inlined:
     sub FLAG_MASK ()   { FLAG_FOO | FLAG_BAR }
 
     sub OPT_BAZ ()     { not (0x1B58 & FLAG_MASK) }
-    sub BAZ_VAL () {
+
+    sub N () { int(OPT_BAZ) / 3 }
+
+    sub FOO_SET () { 1 if FLAG_MASK & FLAG_FOO }
+
+Be aware that these will not be inlined; as they contain inner scopes,
+the constant folding doesn't reduce them to a single constant:
+
+    sub foo_set () { if (FLAG_MASK & FLAG_FOO) { 1 } }
+
+    sub baz_val () {
        if (OPT_BAZ) {
            return 23;
        }
@@ -1142,13 +1152,6 @@ The following functions would all be inlined:
        }
     }
 
-    sub N () { int(BAZ_VAL) / 3 }
-    BEGIN {
-       my $prod = 1;
-       for (1..N) { $prod *= $_ }
-       sub N_FACTORIAL () { $prod }
-    }
-
 If you redefine a subroutine that 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