[Templates] patch: resets component variable to correct value after a PROCESS directive

[Myk Melez]

While evaluating the "component" special variable for something I'm 
working on I noticed that if a template processes another template, the 
first template's component variable is set to the second template's 
component variable afterwards.  In other words, given these two templates:

one:
[% component.name %]
[% PROCESS two %]
[% component.name %]
two:
[% component.name %]
processing the first template results in:

one
two
two
when it should result in:

one
two
one
It looks like this happens in Context.pm's process function, which 
updates the stash with the new component before processing a new 
template but doesn't reset it afterwards.  The attached patch to that 
function fixes the problem by storing the value of that variable before 
processing any templates and then reseting it to that value after 
processing is done.

Note that I eval the variable storage (i.e. eval { $component = 
$stash->get('component') };) to prevent template processing from failing 
in case the stash dies because the variable is not defined (without the 
eval two stash tests fail).  It doesn't matter whether the variable is 
defined or not for our purposes, just that its value before processing 
other templates is the same as its value afterwards, so throwing the 
"value undefined" exception away when the variable isn't defined and 
restoring it to the undefined value afterwards should be exactly what we 
want.

-myk

diff -ur Template-Toolkit-2.10b/lib/Template/Context.pm Template-Toolkit-2.10b-component-fix/lib/Template/Context.pm
--- Template-Toolkit-2.10b/lib/Template/Context.pm	2003-12-02 14:42:12.000000000 +0100
+++ Template-Toolkit-2.10b-component-fix/lib/Template/Context.pm	2004-01-02 20:27:25.000000000 +0100
@@ -293,7 +293,7 @@
     my ($self, $template, $params, $localize) = @_;
     my ($trim, $blocks) = @$self{ qw( TRIM BLOCKS ) };
     my (@compiled, $name, $compiled);
-    my ($stash, $tblocks, $error, $tmpout);
+    my ($stash, $component, $tblocks, $error, $tmpout);
     my $output = '';
 
     $template = [ $template ] unless ref $template eq 'ARRAY';
@@ -318,6 +318,7 @@
     }
 
     eval {
+	eval { $component = $stash->get('component') };
 	foreach $name (@$template) {
 	    $compiled = shift @compiled;
 	    my $element = ref $compiled eq 'CODE' 
@@ -352,6 +353,7 @@
 	    }
 	    $output .= $tmpout;
 	}
+	$stash->set('component', $component);
     };
     $error = $@;