Proper closing of MAD-X Instances

[JoschD]

Hey, I just stumbled upon this behaviour, that the madx instance still accepts commands even after it was closed.
Is this a known "bug"?

Code example:

from cpymad.madx import Madx
madx =  Madx()
madx.input("quit;")
madx.print(text="Still Printing")

with madx.exit() and madx.quit() everything is nicely ended (from the python side),
but a quit, exit, stop in the madx-code or madx.stop() only stops the madx run but still accepts commands.

This can be very annoying when quit is called within a file or macro, the cpymad run continues and runs fine (even reading and setting variables) , sporadically one can find messages like this in the output:

+++ memory access outside program range, fatal +++

but the program still continues to run until you do something fancy,
like a twiss, which fails then with a very non-distinct error message:

++++++ Error: seterrorflag : Errorcode: 1   Reported from pro_twiss:
++++++ Error: seterrorflag : Description: TWISS failed

Not sure if it would make sense to check in the output for:

++++++++++++++++++++++++++++++++++++++++++++
+          MAD-X finished normally         +
++++++++++++++++++++++++++++++++++++++++++++

I understand that this is probably not easy to fix, but maybe it should be included into the known issues.

[coldfix]

Hey,

yeah, I'd probably consider this a user mistake. But you're right, I think adding it to known issues is definitely worth, and we can see later if we want to do anything else about it.

[coldfix]

In principle, we could check for the variables final_message or stop_flag before each command and then raise an Exception if they contain a 1.

automatic restarting would probably be a bad idea (makes it harder for user to find the cause the problem), and automatic cleanup of the MAD-X process + python process by checking the stop condition after each command might also be unexpected (you can probably still retrieve some data from MAD-X, even after a quit was executed, and that might be an important use case for some users)