From: padre@elte.hu <padre@elte.hu>
Date: Fri, 19 Mar 2004 14:56:09 +0000 (+0000)
Subject: Clarifications on constants subroutines, based on:
X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=commitdiff_plain;h=882672714c7b1c946ae8e88a96766a508485d95e;p=p5sagit%2Fp5-mst-13.2.git

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
--- 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