gEDA-user: Global vs local attributes with symbols

[Yamazaki R2 <yamazakir2@xxxxxxxxx>]

   Here is an annoyance I'm experiencing often when it comes to gschem.
   When I instance an symbol in, whether it be a transistor, a subcell,
   or any other random component, all of the attributes are saved in the
   schematic file instead of inherited from the symbol file. This may not
   seem like a huge concern but imagine that you have a fairly large
   hierachrical design where you instanced transistors in from a symbol
   file 100's of times. Lets say the symbol properties of that symbol are
   refdes=M?, l=0.13u,w=1u,device=n3t,bulk=vss,value=n. Now, I bring in a
   new model for that transistor called nmos instead of n. So I go and
   change the symbol file from value=n to value=nmos. But whoops, the
   attributes are local so now I have to open up every schematic and
   changes the transistors one by one instead of editing on symbol file
   and having my whole design inherit the attributes.
   Now with that said, I know inheriting ALL attributes wouldn't make any
   sense. For example you can't have the refdes and w/l inherited.
   However, there should be some way in the symbol file what to inherit
   something by default and making the local version optional. For
   example the way other CAD tools I know of handle this is that each
   instance has a master attribute and a local attribute. If there local
   attribute is blank, it inherits from the master attribute. If the
   local attribute is filled out, then it takes that value of the master.
   refdes should me mandatory, all else should be optional.


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