Re: simpler replacement for <%shared>

> On Tue, 28 Sep 2004, Jonathan Swartz wrote:
> 
>>We can provide almost the same functionality in a simpler, more reliable
>>way with a restricted block that simply declares one or more shared
>>request variables. e.g.
>>    <%request_vars>
>>Beyond implementation simplicity and efficiency, this section has
>>several advantages over <%shared>:
> 
> Can you say anything about the implementation?
> How is it implemented differently from <%shared> variables, or declaring
> "my $var" inside a <%once> section?

It is a much simpler implementation. The "my $var" declarations are 
placed in the same place as <%once> code. At the beginning of the main 
component and each subcomponent/method, we call a local 
'_clear_request_vars' routine that undefs the variables. We also 
register the component with a cleanup list stored in the request, so 
that at the end of the request, Mason calls '_clear_request_vars' again 
on each of these components. The redundant calls are to make absolutely 
sure data doesn't leak between requests.

Guess the easiest way to show it is to check it in. I'll use 
request_vars for the purpose of check-in but acknowledge that the name 
is open to debate.

> 
> 
>>* Mason can automatically cleanup the values of each request var at the
>>end of the request. Variables declared in <%shared> cannot be
>>automatically cleaned up and thus often look like leaks.
> 
> 
> Will it happen even with exceptions and aborts?  (unlike <%cleanup>)

Yes - see above. Fixing <%cleanup> is another matter 
(http://www.masonhq.com/resources/todo/view.html?id=510) but this could 
use the same cleanup registry mechanism as above.

Jon




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