Program exiting gracefully on input

[FredMSloniker 2]

I'd like to write a program where the user can type something at any of several entry prompts and have the program close neatly. What comes to my mind is using xpcall() to call a main loop function, having the code throw up a 'done now' error() whenever it gets the 'quit' input, and have xpcall()'s message handler check for that error and handle it with a 'okay, see you' message, with debug.traceback() being called if any other errors pop out. Is there a better way?

 

[SpiritedDusty 3]

You could use Lua's goto statement.

if evaluateInput() == 'quit' then
  goto quit
elseif evaluateInput() == 'some other stuff' then
  -- continue program
end

::quit::

EDIT: Moved topic to correct section.

[ingie 6]

not sure i really understand the scenario...

 

why is "return value" not appropriate?

[FredMSloniker 2]

not sure i really understand the scenario...

 

why is "return value" not appropriate?

 

Well, it wouldn't work in the middle of a function if I want to quit the entire program.

[ingie 6]

aye, but the calling routine should be checking the return value and exiting gracefully based upon that value...

[Wobbo 8]

Why has nobody mentioned os.exit here yet? That should work just fine. 

[ingie 6]

i thought the op was wanting to check a value prior to the os.exit() or at least, that's how i read it.

 

but yes. otherwise. 

[pedrosgali 8]

I tend to opt for a boolian switch for exiting,

running = true

while running do

run()

end

then you have a variable 'running' which can be toggled. Anywhere.

[ingie 6]

i do the same, aye...

 

tho, for purely personal "purity" reasons, i try to not use the global namespace unless there's no other way, so in that sort of pattern i'd use

 

repeat

  local running = run()

until not running

 

or a similar construct. 

[pedrosgali 8]

In fairness yeah, it should be a local.