some pod cleanups

[gitmo/Moo.git] / lib / Sub / Defer.pm

diff --git a/lib/Sub/Defer.pm b/lib/Sub/Defer.pm
index 816190e..28b3e13 100644 (file)
--- a/lib/Sub/Defer.pm
+++ b/lib/Sub/Defer.pm
@@ -3,6 +3,10 @@ package Sub::Defer;
 use strictures 1;
 use base qw(Exporter);
 use Moo::_Utils;
+use Scalar::Util qw(weaken);
+
+our $VERSION = '1.003001';
+$VERSION = eval $VERSION;
 
 our @EXPORT = qw(defer_sub undefer_sub);
 
@@ -13,25 +17,103 @@ sub undefer_sub {
   my ($target, $maker, $undeferred_ref) = @{
     $DEFERRED{$deferred}||return $deferred
   };
+  return ${$undeferred_ref}
+    if ${$undeferred_ref};
   ${$undeferred_ref} = my $made = $maker->();
-  if (defined($target)) {
+
+  # make sure the method slot has not changed since deferral time
+  if (defined($target) && $deferred eq *{_getglob($target)}{CODE}||'') {
     no warnings 'redefine';
+
+    # I believe $maker already evals with the right package/name, so that
+    # _install_coderef calls are not necessary --ribasushi
     *{_getglob($target)} = $made;
   }
+  weaken($DEFERRED{$made} = $DEFERRED{$deferred});
+
   return $made;
 }
 
+sub defer_info {
+  my ($deferred) = @_;
+  $DEFERRED{$deferred||''};
+}
+
 sub defer_sub {
   my ($target, $maker) = @_;
   my $undeferred;
-  my $deferred_string;
+  my $deferred_info;
   my $deferred = sub {
-    goto &{$undeferred ||= undefer_sub($deferred_string)};
+    $undeferred ||= undefer_sub($deferred_info->[3]);
+    goto &$undeferred;
   };
-  $deferred_string = "$deferred";
-  $DEFERRED{$deferred} = [ $target, $maker, \$undeferred ];
-  *{_getglob $target} = $deferred if defined($target);
+  $deferred_info = [ $target, $maker, \$undeferred, $deferred ];
+  weaken($DEFERRED{$deferred} = $deferred_info);
+  _install_coderef($target => $deferred) if defined $target;
   return $deferred;
 }
 
+sub CLONE {
+  %DEFERRED = map { defined $_ ? ($_->[3] => $_) : () } values %DEFERRED;
+  weaken($_) for values %DEFERRED;
+}
+
 1;
+__END__
+
+=head1 NAME
+
+Sub::Defer - defer generation of subroutines until they are first called
+
+=head1 SYNOPSIS
+
+ use Sub::Defer;
+
+ my $deferred = defer_sub 'Logger::time_since_first_log' => sub {
+    my $t = time;
+    sub { time - $t };
+ };
+
+  Logger->time_since_first_log; # returns 0 and replaces itself
+  Logger->time_since_first_log; # returns time - $t
+
+=head1 DESCRIPTION
+
+These subroutines provide the user with a convenient way to defer creation of
+subroutines and methods until they are first called.
+
+=head1 SUBROUTINES
+
+=head2 defer_sub
+
+ my $coderef = defer_sub $name => sub { ... };
+
+This subroutine returns a coderef that encapsulates the provided sub - when
+it is first called, the provided sub is called and is -itself- expected to
+return a subroutine which will be goto'ed to on subsequent calls.
+
+If a name is provided, this also installs the sub as that name - and when
+the subroutine is undeferred will re-install the final version for speed.
+
+=head2 undefer_sub
+
+ my $coderef = undefer_sub \&Foo::name;
+
+If the passed coderef has been L<deferred|/defer_sub> this will "undefer" it.
+If the passed coderef has not been deferred, this will just return it.
+
+If this is confusing, take a look at the example in the L</SYNOPSIS>.
+
+=head1 SUPPORT
+
+See L<Moo> for support and contact information.
+
+=head1 AUTHORS
+
+See L<Moo> for authors.
+
+=head1 COPYRIGHT AND LICENSE
+
+See L<Moo> for the copyright and license.
+
+=cut