On Thu, Jul 14, 2005 at 01:33:54AM -0700, Michael G Schwern via RT wrote:
> > [EMAIL PROTECTED] - Sun Jun 23 02:21:24 2002]:
> >
> > Having tried to share objects by writing stuff along the lines:
> >
> > my $a : shared = new FOOBAR;
> >
> > It took a posting to comp.lang.perl.misc before I realised the error
> > of my ways:
> >
> > my $a = new FOOBAR;
> > share($a);
> >
> > I don't think the threads::shared and perlthrtut docs make this clear
> > enough -
> > folks coming to ithreads from Java etc are going to finds things a bit
> > odd to
> > begin with.
> >
> > SOLUTION: More examples in the docs please, esp. regarding object
> > sharing. Also
> > maybe trim down some of the general threading info in perlthrtut with
> > more
> > focus on perl threads and how to use them idiomatically.
>
> threads::shared and perlthrtut still lacks this additional documentation.
How about this:
--
"The greatest achievement of the Austrians has been convincing the world
that Hitler was German, and Mozart Austrian."
Change 25161 by [EMAIL PROTECTED] on 2005/07/17 20:54:15
[perl #9720] document what can be assigned to a shared scalar
Affected files ...
... //depot/perl/ext/threads/shared/shared.pm#38 edit
Differences ...
==== //depot/perl/ext/threads/shared/shared.pm#38 (text) ====
@@ -53,6 +53,10 @@
use threads::shared;
my $var : shared;
+ $var = $scalar_value;
+ $var = $shared_ref_value;
+ $var = &share($simple_unshared_ref_value);
+ $var = &share(new Foo);
my($scalar, @array, %hash);
share($scalar);
@@ -101,6 +105,9 @@
C<share> will traverse up references exactly I<one> level.
C<share(\$a)> is equivalent to C<share($a)>, while C<share(\\$a)> is not.
+This means that you must create nested shared data structures by first
+creating individual shared leaf notes, then adding them to a shared hash
+or array.
A variable can also be marked as shared at compile time by using the
C<shared> attribute: C<my $var : shared>.
@@ -109,6 +116,20 @@
need to use C<&share([])> and C<&share({})> syntax due to problems
with Perl's prototyping.
+The only values that can be assigned to a shared scalar are other scalar
+values, or shared refs, eg
+
+ my $var : shared;
+ $var = 1; # ok
+ $var = &share([]); # ok
+ $var = []; # error
+ $var = A->new; # error
+ $var = &share(A->new); # ok as long as the A object is not nested
+
+Note that it is often not wise to share an object unless the class itself
+has been written to support sharing; for example, an object's destructor
+may get called multiple times, one for each thread's scope exit.
+
=item lock VARIABLE
C<lock> places a lock on a variable until the lock goes out of scope.
