Re: gEDA-user: gerbv - abnormal exit (2nd attempt)

[wilson1442@xxxxxxxxxxxxx]

Stefan Petersen wrote:

> 2) The aperture macro also contains operations like $4=$1X$5.

My copy of "Gerber Format: Plot Data Format Reference Book" is quite 
old, (c)1993.  But some of the examples use the "$4=" construct to work 
around the severe restriction on expressions:

   "Only one operator is allowed between commas.", and
   "Only one operator is allowed on the right side of the equals sign."

If one wants to do anything remotely fancy, one almost has to use this 
gimmick.  I wonder if these restrictions have been eased lately?  Even 
simple left-to-right without operator precedence would be a big step up.

I seem to remember running into this problem back with V1.0.2, and 
thought I might take a whack at fixing it, but I recall gerbv is written 
mostly in Scheme.  To me, it might as well have been written in 
Boustrophedon.  I know that Scheme is a beautiful language, and I've 
taken a couple of stabs at learning it, but  I still don't know my cdr 
from a hole in the ground!

Back then, I eventually found a web based viewer hosted on a server by 
Scott Ananian which did grok the expressions correctly (as far as I 
could tell), but Scott got his PhD and the server which sat under his 
desk at MIT is no more.  He sent me his Java sources which must be 
served up by Tomcat.  To me, it's more Boustrophedon!

Thank you Stefan for checking my stuff.  I hope it stack dumps for you 
so you'll have an easy time fixing it.  I understand your reluctance to 
change your parser when it does everything you need for gEDA.

I may have a look at gerber2pdf.  At least it's written in Python, a 
language I use often, and there may be some hope of understanding it.

Thanks again for looking.

Jim


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