gEDA-user: updating footprints in an existing layout

[Dan McMahill <dan@xxxxxxxxxxxx>]

trying again on geda-user due to deafening silence on geda-dev...

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Hi,

I'm trying to understand what method various layout tools use for 
updating footprints in an existing design.  If you have experience with 
various layout tools and could tell me about the following, I'd greatly 
appreciate it.


- How do you check to see if you have footprints in your design which 
are out of date with your footprint library?

- How do you distinguish changes like moving the RefDes silk screen or 
increasing soldermask clearance (thing you could reasonable expect to 
change on a particular board) vs. changes like pinout or pin pitch 
(things you wouldn't normally change during a design)?  The latter of 
course being one which may make you want to update the footprint.

- Once you have identifed an instance as being out of date, how do you 
see the difference between your footprint and the new one in the library?

- How does the footprint in your layout know where the master lives in 
the library?  Does the layout just contain a reference to the library? 
Does the layout embed the footprint?  Do you look up the footprint by 
just searching for a name through a predefined search path or does it 
search for the footprint in a particular library/sublibrary/whatever?

- How do you update all out of date footprints in the design?  How about 
just all instances of a particular footprint?  How about just a single 
instance of one footprint?

- How do you avoid resetting things like RefDes silk screen 
size/orientation/location when you update a footprint?


As you might gather from this, I'm trying to work up a proposal for how 
footprints should be updated in pcb and I want to try and have it well 
thought out before any code is written.

Thanks for any info you can provide.

-Dan