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From Sylvain Wallez <>
Subject Re: overloading sitemap variable names
Date Mon, 14 Oct 2002 08:25:38 GMT
Conal Tuohy wrote:

>>-----Original Message-----
>>From: Geoff Howard []
>>How would this name overloading work with respect to:
>>- references from resources back to their calling pipeline
>>- from a subsitemap back to the mounting reference
>>Seems these cases may make overloading desireable.
>>Geoff Howard
>I have some reservations at least about the 2nd case. I would be interested
>to hear what other people think, because it seems to me that the practice of
>a child block referring to named components within the parent block is a
>complication worth avoiding.
>It seems to me that a child block should not, as a matter of principle,
>depend on its parent block containing a component with a particular
>variable-name. This would complicate the interface between blocks, and make
>it difficult to re-use them.
>AFAIR the original plan for blocks envisaged information being passed only
>in the URI, and if the child block needed access to some data from the
>parent then the parent block could pass that data in the map:mount call,
>avoiding a dependency on any particular name (effectively passing it as a

I agree with you, even if we're talking here of sub-sitemap, and not 
blocks which are a still-to-be-defined beast.

Resources are an integral part of a sitemap (think of it as a reusable 
pipeline snippet, or a subroutine), and thus named variables are visible 
from resources as from any other place in the sitemap.

Mounting is a different thing, and passing named variables to 
subsitemaps would introduce a coupling with the parent sitemap that 
isn't desirable.


Sylvain Wallez
  Anyware Technologies                  Apache Cocoon 

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