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From Glen Mazza <grm7...@yahoo.com>
Subject Re: String.intern() thoughts
Date Thu, 04 Dec 2003 12:58:23 GMT
Thanks for the explanation.

Glen

--- "Peter B. West" <pbwest@powerup.com.au> wrote:
> Glen Mazza wrote:
> ...
> > 
> > I think the next thing to consider is the storage
> of
> > specified vs. computed values.  Let's say we store
> > pointers for many properties to the same
> > {"property-name", "property-value"} pair.  A
> specified
> > property value of "10%" would not make this a very
> > helpful data structure if that percentage resolves
> to
> > different computed values for each property
> sharing
> > this pair.  I believe the goal for us then would
> be
> > just store the computed value for each pair
> (meaning
> > many more pairs), as long as we take into account
> the
> >
> can't-resolve-everything-without-knowledge-of-layout
> > issue.
> 
> alt.design makes no attempt to look for
> commonalities here.  It resolves 
> every possible property value, and keeps a
> partly-resolved value for 
> percentages.  Inheritance is (almost exclusively) of
> computed values.
> <quote>
> For a given inheritable property, if that property
> is present on a 
> child, then that value of the property is used for
> that child (and its 
> descendants until explicitly re-set in a lower
> descendant); otherwise, 
> the specified value of that property on the child is
> the computed value 
> of that property on the parent formatting object.
> </quote> 5.1.4 Inheritance
> 
> There is an exception that comes to mind.  For
> "line-height" a value may 
> be specified which, although not specified as a
> percentage, is a factor 
> by which the font-size (from memory) is multiplied. 
> When such a value 
> is inherited, it is the factor, not the computed
> value.
> 
> In general, the computed value of a percentage is
> inherited.  That still 
> leaves a problem, because the computed value is
> unknown.  In alt.design, 
> what is effectively a link back to the unresolved
> property is specified 
> as the value.  When the parent property is resolved,
> that resolved value 
> is then available to the inheriting descendants.
> 
> Yet-to-be-implemented is the handling of expressions
> involving 
> percentages, as mentioned in an earlier post.
> 
> In essence, alt.design attempts to resolve every
> property to its 
> computed value, and store the result only on nodes
> to which the property 
> applies.  There is no attempt to reduce storage by
> procedures like 
> interning strings.  Note, though, that the process
> of resolving 
> properties does eliminate most strings.  My
> objective was that when 
> areas were being laid out, the relevant properties
> would all be directly 
> available.
> 
> Peter
> -- 
> Peter B. West
> <http://www.powerup.com.au/~pbwest/resume.html>
> 


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