[cad-linux] Re: symlinks as blocks, parts, etc
- From: Eric Wilhelm <ewilhelm@xxxxxxxxxxxxx>
- To: cad-linux@xxxxxxxxxxxxx
- Date: Wed, 17 Sep 2003 19:09:11 -0500
> The following was supposedly scribed by
> phrostie
> on Wednesday 17 September 2003 06:06 pm:
>i liked the symlink idea.
>most cad systems have some form of sharing geometry.
>they all have their own names whether it blocks, details, patterns, dittos,
>instances, or what ever. don't chunck the symlink idea just yet.
The difficulty is to get a method of linking geometry that is flexible and
usable by all of these systems.
Also, how would you describe such things as "attributes". Possibly the
inserted item has a file (or item) in the model tree that represents that
entity and holds values specific to that instance.
Example:
In the openDWG toolkit (apparently (I've yet to try using them)) a block has a
structure associated with its definition, and a member of that structure
holds a blockobjhandle (or whatever they call it) which is read with the same
methods as a drawing (I think that each instance of the block must have a
pointer to the same content-definition memory address.)
I don't think a symlink is really the appropriate way to handle this (and I'm
not quite sold on the parceled-out files approach either) but it may be a
good way to think about it as a starting point. Maybe the definition is via
one entity which holds the attributes for the instance and a pointer to the
data object (or the root of the tree which defines the block.)
This pointer could be a url.
The data in the block could be the toplevel of a fs tree or maybe a file with
a list of url-attribute pairs. The root of the tree would be the most
dynamically defined setup.
--Eric
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