Feedback wanted: conditional GCode without indentation

[fcwilt]

@DaveA said in Feedback wanted: conditional GCode without indentation:

As a C & C++ programmer from around 1976 I'd love to see the Kernighan and Ritchie style with { } syntax. I hate Python indention style.
Just my opinion since you asked.

Ugh - no.

C++ syntax was devised by sadists.

Frederick

[DaveA]

@fcwilt Yeah, I can agree with you on C++. I'd rather stick with straight C as most of my experience was with windows device drivers. In any case, it's better than Python.

[zapta]

@fcwilt said in Feedback wanted: conditional GCode without indentation:

END by itself is easy but if you don't see it in context you don't know what it is the end of. It might be better to have unique keywords - ENDWHILE, ENDIF or something along those lines.
Frederick

One option is to annotate it with comments.

END ; while xyz

BTW, I am also not a fan of white space indentation having semantic meaning. It's too fragile, event with language specific editors that support it.

[reghend79]

I think both keyword-delimiting and indentation-delimiting should be permitted in the same file to allow for flexibility and varying degrees of clarity. I'm working on analyzing print data in Matlab to create feedback control, and I am quite fond of using both indentations and "end" statements at the same time. The indentations are not normally required in Matlab, but they're done automatically to help visualize the blocks.

[zapta]

@reghend79 said in Feedback wanted: conditional GCode without indentation:

The indentations are not normally required in Matlab, but they're done automatically to help visualize the blocks.

That's a good point, END should still allow indentation for code clarity, though the indentation would have no semantic impact. E.g. these code snippet should have the same meaning

            IF
     COMMAND1
  COMMAND2
COMMAND3
    END


IF
COMMAND1
COMMAND2
END


IF
    COMMAND1
    COMMAND2
    END

IF
    COMMAND1
    COMMAND2
END

[fcwilt]

@zapta said in Feedback wanted: conditional GCode without indentation:

One option is to annotate it with comments.

END ; while xyz

True but with specific keywords I'm forced to do the "right" thing.

Frederick

[alankilian]

Here's one way to "DO" it.

https://www.cnccookbook.com/cnc-g-code-macro-conditions-looping/

[garyd9]

@fcwilt said in Feedback wanted: conditional GCode without indentation:

@garyd9 said in Feedback wanted: conditional GCode without indentation:

Can you please give an example of a gcode sequence that would impractical with the current space delimiting blocks?

The issue is gcode files as generated by a slicer - not the files you would create yourself on the duet.

That doesn't answer the question. Without an example of the problem, it's difficult to give a reasonable opinion on a proposed solution.

[bot]

I think removing all indentation/whitespace from the syntax is a good idea. I also think a single END keyword is best. Multiple end keywords is just unnecessary. Keep track of the ENDs the same way one keeps track of the }s.

[fcwilt]

@garyd9 said in Feedback wanted: conditional GCode without indentation:

That doesn't answer the question. Without an example of the problem, it's difficult to give a reasonable opinion on a proposed solution.

As dc42 said in his opening post:

However, the need to indent the body of a conditional or loop makes it impractical to use a while-loop to create a looping GCode file, for example for a belt printer.

That seems clear enough.

Frederick

[dc42]

@garyd9 said in Feedback wanted: conditional GCode without indentation:

@fcwilt said in Feedback wanted: conditional GCode without indentation:

@garyd9 said in Feedback wanted: conditional GCode without indentation:

Can you please give an example of a gcode sequence that would impractical with the current space delimiting blocks?

The issue is gcode files as generated by a slicer - not the files you would create yourself on the duet.

That doesn't answer the question. Without an example of the problem, it's difficult to give a reasonable opinion on a proposed solution.

Suppose you generate a GCode file using a slicer. But you have a belt printer and you want to print it 10 times, with a belt movement between each iteration.

Using existing slicers, there is no way to use the slicer start and end scripts to achieve this.

You could achieve it by editing the GCode file, but then you would have to indent almost the whole GCode file so that it became the body of the while-loop.

If we offer the option to delimit if- and while-commands explicitly, then you could insert one line near the start of the file (the 'while' line), and one near the end (the 'end' line). You might even be able to put the 'while' line in your slicer start script, and the 'end' line in the end script, so that you don't need to edit the file at all.

Does that make the reason for this proposal clearer?

[fcwilt]

@bot said in Feedback wanted: conditional GCode without indentation:

Keep track of the ENDs the same way one keeps track of the }s.

'}' symbols are evil incarnate.

Frederick

[bot]

@fcwilt } // they don't seem so bad to me

[tekkydave]

@dc42 curly braces for me every time. I don't see the point of adding extra keywords that just take up space.

[tekkydave]

@fcwilt I once used a language called pl/9 that had a repeat...until. I miss it from every other language I've used since.

[fcwilt]

@tekkydave said in Feedback wanted: conditional GCode without indentation:

@fcwilt I once used a language called pl/9 that had a repeat...until. I miss it from every other language I've used since.

I never heard of PL/9 - I used PL/1 for a bit - it's looping syntax was flexible and consistent.

My programming language of choice is Delphi.

Frederick

[fcwilt]

@tekkydave said in Feedback wanted: conditional GCode without indentation:

@dc42 curly braces for me every time. I don't see the point of adding extra keywords that just take up space.

Keywords have a mnemonic value that isolated arbitrary symbols lack.

Frederick

[garyd9]

@dc42 said in Feedback wanted: conditional GCode without indentation:

Does that make the reason for this proposal clearer?

Yes, much clearer. Thank you.

I'm not familiar with belt printers and how this might be used - which left (and still leaves) my understanding lacking.

That being said, can the problem be addressed using macros? Can a print job's gcode use M28/M29 to create new files?

; ----- start gcode
;
; inital printer setup
; 
M28 job.gcode ; cause the actual gcode to be written to job.gcode
;
; ------- actual print gcode generated by slicer
;
; --------- end gcode
M29  ; stop/save job.gcode
;
;  -- here would be the loop for running the print job
while (some_condition)
       ; belt movement
       M32 job.gcode

<eof>

(I have no idea if a gcode file can use M28/m29 to create another gcode file, but if it can...)

[theruttmeister]

@dc42 said in Feedback wanted: conditional GCode without indentation:

@garyd9 said in Feedback wanted: conditional GCode without indentation:

@fcwilt said in Feedback wanted: conditional GCode without indentation:

@garyd9 said in Feedback wanted: conditional GCode without indentation:

Can you please give an example of a gcode sequence that would impractical with the current space delimiting blocks?

The issue is gcode files as generated by a slicer - not the files you would create yourself on the duet.

That doesn't answer the question. Without an example of the problem, it's difficult to give a reasonable opinion on a proposed solution.

Suppose you generate a GCode file using a slicer. But you have a belt printer and you want to print it 10 times, with a belt movement between each iteration.

Using existing slicers, there is no way to use the slicer start and end scripts to achieve this.

You could achieve it by editing the GCode file, but then you would have to indent almost the whole GCode file so that it became the body of the while-loop.

If we offer the option to delimit if- and while-commands explicitly, then you could insert one line near the start of the file (the 'while' line), and one near the end (the 'end' line). You might even be able to put the 'while' line in your slicer start script, and the 'end' line in the end script, so that you don't need to edit the file at all.

Does that make the reason for this proposal clearer?

That could be simplified down to a gcode command that executed a specific .gcode file multiple times:
Mxxx thisprintjob.gcode S10
For example.
That has the advantage of not needing anything like the complexity of conditionals.

I think the fact that it is a programming loop is making people think that the solution is to create the ability in g-code to code loops. Where as in fact for the described use case at least, its not really a loop, its just a way to not have the file be 10 times longer than it needs to be.

At there other things that actually are conditional and not just 'do x, y number of times'?

(in fact, all this could be done in DWC... which in some ways makes more sense).

[zapta]

@fcwilt said in Feedback wanted: conditional GCode without indentation:

'}' symbols are evil incarnate.

The Duet's firmware is full of them, don't bring it into your home.

https://github.com/Duet3D/RepRapFirmware/blob/dev/src/Movement/DriveMovement.cpp