--- AnyEvent/lib/AnyEvent.pm	2009/07/30 03:41:56	1.266
+++ AnyEvent/lib/AnyEvent.pm	2009/08/06 13:31:01	1.272
@@ -401,18 +401,22 @@
 =head3 Signal Races, Delays and Workarounds
 
 Many event loops (e.g. Glib, Tk, Qt, IO::Async) do not support attaching
-callbacks to signals in a generic way, which is a pity, as you cannot do
-race-free signal handling in perl. AnyEvent will try to do it's best, but
-in some cases, signals will be delayed. The maximum time a signal might
-be delayed is specified in C<$AnyEvent::MAX_SIGNAL_LATENCY> (default: 10
-seconds). This variable can be changed only before the first signal
-watcher is created, and should be left alone otherwise. Higher values
+callbacks to signals in a generic way, which is a pity, as you cannot
+do race-free signal handling in perl, requiring C libraries for
+this. AnyEvent will try to do it's best, which means in some cases,
+signals will be delayed. The maximum time a signal might be delayed is
+specified in C<$AnyEvent::MAX_SIGNAL_LATENCY> (default: 10 seconds). This
+variable can be changed only before the first signal watcher is created,
+and should be left alone otherwise. This variable determines how often
+AnyEvent polls for signals (in case a wake-up was missed). Higher values
 will cause fewer spurious wake-ups, which is better for power and CPU
-saving. All these problems can be avoided by installing the optional
-L<Async::Interrupt> module. This will not work with inherently broken
-event loops such as L<Event> or L<Event::Lib> (and not with L<POE>
-currently, as POE does it's own workaround with one-second latency). With
-those, you just have to suffer the delays.
+saving.
+
+All these problems can be avoided by installing the optional
+L<Async::Interrupt> module, which works with most event loops. It will not
+work with inherently broken event loops such as L<Event> or L<Event::Lib>
+(and not with L<POE> currently, as POE does it's own workaround with
+one-second latency). For those, you just have to suffer the delays.
 
 =head2 CHILD PROCESS WATCHERS
 
@@ -788,10 +792,10 @@
 This is a mutator function that returns the callback set and optionally
 replaces it before doing so.
 
-The callback will be called when the condition becomes "true", i.e. when
-C<send> or C<croak> are called, with the only argument being the condition
-variable itself. Calling C<recv> inside the callback or at any later time
-is guaranteed not to block.
+The callback will be called when the condition becomes (or already was)
+"true", i.e. when C<send> or C<croak> are called (or were called), with
+the only argument being the condition variable itself. Calling C<recv>
+inside the callback or at any later time is guaranteed not to block.
 
 =back
 
@@ -1113,7 +1117,7 @@
 
 use Carp ();
 
-our $VERSION = 4.881;
+our $VERSION = 4.901;
 our $MODEL;
 
 our $AUTOLOAD;
@@ -1632,8 +1636,14 @@
 }
 
 sub cb {
-   $_[0]{_ae_cb} = $_[1] if @_ > 1;
-   $_[0]{_ae_cb}
+   my $cv = shift;
+
+   @_
+      and $cv->{_ae_cb} = shift
+      and $cv->{_ae_sent}
+      and (delete $cv->{_ae_cb})->($cv);
+
+   $cv->{_ae_cb}
 }
 
 sub begin {
@@ -1676,8 +1686,8 @@
    AnyEvent->idle (cb => $_[0]);
 }
 
-sub cv() {
-   AnyEvent->condvar
+sub cv(;&) {
+   AnyEvent->condvar (@_ ? (cb => $_[0]) : ())
 }
 
 sub now() {