From: Rafael Garcia-Suarez <rgarciasuarez@gmail.com>
Date: Sat, 6 Dec 2003 19:58:51 +0000 (+0000)
Subject: Remove the "Can't provide tied hash usage" error from perldiag.
X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=commitdiff_plain;h=085bcbb1d33da8a158e1316d85fae9d242baf2d0;p=p5sagit%2Fp5-mst-13.2.git

Remove the "Can't provide tied hash usage" error from perldiag.
Mention the new tied hash SCALAR method in perldelta.

p4raw-id: //depot/perl@21857
---

diff --git a/pod/perldelta.pod b/pod/perldelta.pod
index f8b5dea..9ebb2ed 100644
--- a/pod/perldelta.pod
+++ b/pod/perldelta.pod
@@ -216,6 +216,22 @@ contains a package variable named C<$NEGATIVE_INDICES> which is set to
 a true value, negative values will be passed to C<FETCH>, C<STORE>,
 C<EXISTS>, and C<DELETE> unchanged.
 
+=head2 Tied hashes in scalar context
+
+As of perl 5.8.2, tied hashes did not return anything useful in scalar
+context, for example when used as boolean tests:
+
+	if (%tied_hash) { ... }
+
+The old nonsensical behaviour was always to return false,
+regardless of whether the hash is empty or has elements.
+
+There is now an interface for the implementors of tied hashes to implement
+the behaviour of a hash in scalar context, via the SCALAR method (see
+L<perltie>).  Without a SCALAR method, perl will try to guess whether
+the hash is empty, by testing if it's inside an iteration (in this case
+it can't be empty) or by calling FIRSTKEY.
+
 =head2 local ${$x}
 
 The syntaxes
@@ -861,19 +877,6 @@ common Perl platforms (Unix and Unix-like, Microsoft platforms, and
 VMS) have large enough testing and expert population that they are
 doing well.
 
-=head2 Tied hashes in scalar context
-
-Tied hashes do not currently return anything useful in scalar context,
-for example when used as boolean tests:
-
-	if (%tied_hash) { ... }
-
-The current nonsensical behaviour is always to return false,
-regardless of whether the hash is empty or has elements.
-
-The root cause is that there is no interface for the implementors of
-tied hashes to implement the behaviour of a hash in scalar context.
-
 =head2 Net::Ping 450_service and 510_ping_udp failures
 
 The subtests 9 and 18 of lib/Net/Ping/t/450_service.t, and the
diff --git a/pod/perldiag.pod b/pod/perldiag.pod
index 2b98439..2fb8615 100644
--- a/pod/perldiag.pod
+++ b/pod/perldiag.pod
@@ -911,14 +911,6 @@ for stdout.
 
 (F) The script you specified can't be opened for the indicated reason.
 
-=item Can't provide tied hash usage; use keys(%hash) to test if empty
-
-(F) When a hash is evaluated in scalar context, bucket usage is
-returned if the hash is populated, and false is returned if the hash
-is empty.  Bucket usage is not currently available for tied hashes.
-To test if a hash is empty or populated, use keys(%hash) in scalar
-context instead.
-
 =item Can't read CRTL environ
 
 (S) A warning peculiar to VMS.  Perl tried to read an element of %ENV