feature request: --skip_layer option for strmxor

[stefanottili]

It would be nice if one could skip one or multiple layers using strmxor, similar to klayout's "xor only visible layers".

E.g. skip all base and tile layer if you're only interested in metal differences.

[klayoutmatthias]

Actually, this is already possible through the layer mapping feature:

For example, if you like to exclude layers 10 to 12, datatype 0 and all datatypes of layer 15, you can use:

strmxor -am "[*/*] -(10-12/0) -(15/*)" -as -bm "[*/*] -(10-12/0) -(15/*)" -bs a.gds b.gds xor.gds

"-as" and "-bs" (skip unknown layers) is necessary, so the reader won't add the unmapped layers again.

Matthias