perlfunc.pod grammar fixes

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

diff --git a/pod/perlmod.pod b/pod/perlmod.pod
index 752d1f3..99d08eb 100644 (file)
--- a/pod/perlmod.pod
+++ b/pod/perlmod.pod
@@ -539,15 +539,35 @@ between different threads. These threads can be used by using the C<threads>
 module or by doing fork() on win32 (fake fork() support). When a
 thread is cloned all Perl data is cloned, however non-Perl data cannot
 be cloned automatically.  Perl after 5.7.2 has support for the C<CLONE>
-special subroutine .  In C<CLONE> you can do whatever you need to do,
+special subroutine.  In C<CLONE> you can do whatever
+you need to do,
 like for example handle the cloning of non-Perl data, if necessary.
-C<CLONE> will be executed once for every package that has it defined
-(or inherits it).  It will be called in the context of the new thread,
-so all modifications are made in the new area.
+C<CLONE> will be called once as a class method for every package that has it
+defined (or inherits it).  It will be called in the context of the new thread,
+so all modifications are made in the new area.  Currently CLONE is called with
+no parameters other than the invocant package name, but code should not assume
+that this will remain unchanged, as it is likely that in future extra parameters
+will be passed in to give more information about the state of cloning.
 
 If you want to CLONE all objects you will need to keep track of them per
 package. This is simply done using a hash and Scalar::Util::weaken().
 
+Perl after 5.8.7 has support for the C<CLONE_SKIP> special subroutine.
+Like C<CLONE>, C<CLONE_SKIP> is called once per package; however, it is
+called just before cloning starts, and in the context of the parent
+thread. If it returns a true value, then no objects of that class will
+be cloned; or rather, they will be copied as unblessed, undef values.
+This provides a simple mechanism for making a module threadsafe; just add
+C<sub CLONE_SKIP { 1 }> at the top of the class, and C<DESTROY()> will be
+now only be called once per object. Of course, if the child thread needs
+to make use of the objects, then a more sophisticated approach is
+needed.
+
+Like C<CLONE>, C<CLONE_SKIP> is currently called with no parameters other
+than the invocant package name, although that may change. Similarly, to
+allow for future expansion, the return value should be a single C<0> or
+C<1> value.
+
 =head1 SEE ALSO
 
 See L<perlmodlib> for general style issues related to building Perl