Re: gEDA-user: General Layers questions

[Stephan Boettcher <boettcher@xxxxxxxxxxxxxxxxxx>]

DJ Delorie <dj@xxxxxxxxxxx> writes:

>> I don't want to end up with the current state that some 'specialy
>> named' layers receive special treatment.
>
>>From a practical standpoint, I think it makes sense to have a fast way
> to scan for layers of some high-level type, as well as further typing
> them by name.

I do not agree with the term high level here.  I agree that there may be
layers of different types, that require special treatment.  These are
low-level types, like "conductive" for layers that electrically connect
things, or "holes" for connections between layers, and "other" for
anything else.  What kind of high-performance processing is needed in
addition to that?  Well, when you figure out that there is something
else, it's a good justification to add anothe type.

At the storage data level they are still all layers with attributes.
When loading the layout, they are collected into separate lists, or get
a binary attribute attached, by enumerating known values of the
attribute "pcb:type="

> My original design had an enumerated type for each drawing layer, that
> was one of (for example) "copper, silk, soldermask, paste, outline,
> other" with flags for "normal, inverted" and an assignment to a
> physical layer (1..N).
>
> That way, when you're doing something compute-intensive like
> connectivity checks for "auto-enforce drc clearance" you aren't doing
> a bazillion string compares.
>
> Actions that are performed less often, like mapping a footprint to an
> element, can use a more open-ended string-attribute with more complex
> rules.

-- 
Stephan


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