[Design] Re: Design Digest, Vol 29, Issue 4

[Alec Flett]

Andi Vajda wrote:
>
> The InclusionExclusionCollection class, however, does implement 'add' 
> and 'remove'. With that implementation, it can decide whether to force 
> an attribute value to fit a filter expression or whether to append the 
> item to its inclusions ListCollection, bypassing the filter.
I think overriding the 'add' method to do what we want is one thing - I 
think the art is in choosing /when/ to add the item to inclusions, and 
when to modify the item itself.. that is a semantic issue, which depends 
on the particular type of object being added, and the base collection in 
the InclusionExclusionCollection...

I think right now we're talking about an explicit list of attributes 
right now. Eventually I'd like some way of attaching metadata to 
attributes themselves, to indicate which attributes cause item 
modifications when adding to a collection, and which ones cause the item 
to be added to a list of inclusions.

Alec
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