On 10/30/2013 01:41 PM, andy pugh wrote: > Whist not wanting to defend G-code, which is, as you say, horrible as > a programming language, it does already contain G-codes to switch > between units and (At least with the LinuxCNC variant) repeating > patterns are reasonably manageable with the use of subroutines, loops > and conditionals.
The unit switching (G20/G21) makes life more difficult (IMO) in all cases where you have to calculate your position in a mixed setup. It is much easier to associate a unit to a variable and let it be converted automatically. It is less error-prone. Secondly, reading G-code that switches between units is a real hell. The problem is that you have to keep track manually (in your mind) which unit target is active. Again, very error prone. The loops and conditionals provided by G-code are, well, archaic. The format is context-sensitive and uses line numbers to keep track. Moving things around in a G-code program is a pain. The reason for a context-free grammar is to make coding more flexible without having to think about line numbers. A paradigm that has proven to be very successful. >> I looked for a meta compiler or generic pre-processor, but could not >> find anything that satisfied me. Being able to program should be "easy". > There is an alternative (and possibly more interesting) approach, you > could develop your meta-language into an alternative interpreter for > LinuxCNC. > The interpreter doesn't _have _ to read G-code. It is just that the > only one we have does so. Pluggable interpreters have been an option > for a while. That would certainly be an option for future development. However, my first milestone was to be compatible with existing setups (primarily to make my own stuff). That is to say, I could have written my G-code program that started this project in two days. Instead I opted for using two weeks making gcmc. :-) For a future as a secondary/pluggable interpreter, it would be required to finalize the grammar, discuss required built-in functionality, discuss how to handle rotational axes and get a grip on all bugs. I think it would be a great idea, but I do not want to rush things. -- Greetings Bertho (disclaimers are disclaimed) ------------------------------------------------------------------------------ Android is increasing in popularity, but the open development platform that developers love is also attractive to malware creators. Download this white paper to learn more about secure code signing practices that can help keep Android apps secure. http://pubads.g.doubleclick.net/gampad/clk?id=65839951&iu=/4140/ostg.clktrk _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
