Layers a la PIE/Us

Jecel Assumpcao Jr jecel at merlintec.com
Mon Mar 11 00:41:00 UTC 2002


On Sunday 10 March 2002 02:04, Anthony Hannan wrote:
> I want to propose a design for loadable/unloadable image changes.  It
> is based on layers found in PIE[1] and Us[2], and is designed to work
> on any objects (eg. code modules, morphic projects, etc).

Your idea seems very nice, but too static for my taste. PIE and Us 
allow different layer arrangements to co-exist in memory at the same 
time. My impression is that you want to use layers like modules in that 
they patch objects when they are loaded into memory, so there could be 
compatibility problems.

One thing I didn't like about Us is that layers are grouped by their 
layerParent links and the first layer in a list doubles as a 
"viewpoint" object. PIE has a separate context object for grouping 
layers so that the same layer can be used differently in different 
situations (you need to clone the layer in Us to get that effect).

I have found a neat way to implement layers and contexts so they can be 
used dynamically, but unfortunately it requires a Jitter and won't work 
on an interpreter. I haven't updated my own design to reflect this new 
design, but you might find one or two interesting ideas in:

   http://www.merlintec.com:8080/software/8

-- Jecel



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