CODEWITHSUNDEEP
lua
Shejo284
Shejo284

Reputation: 4771

Catch back trace information without exit

I'm trying to run a series of tests and collect some meta data on each test. If there is an error during one of the tests, I would like to save the back trace information but not to exit the script. For example:

-- Example program

for _, v in ipairs(tests) do
     --check some results of function calls
  if v == nil then
     --error("function X failed") no exit
     --save back trace to variable/file
     -- continue with program 
  end 
 end

I'm not currently aware if it is possible in lua to tell the function error() not to stop after creating the back trace. Any thoughts on how to do this?

Upvotes: 1

Views: 83

Answers (1)

DarkWiiPlayer
DarkWiiPlayer

Reputation: 7064

debug.traceback ([thread,] [message [, level]]) (source) is what you're looking for. You can write a function that 1. gets a traceback 2. opens a file 3. writes the traceback to the file 4. closes the file.

In that case you'd have to use a level of 2, since 0 would be the debug.traceback function, 1 would be the function calling it (i.e. your function) and 2 the funcion calling that one. message could be your error code. Then you just override the error function locally in your script and you're done; calling error will just log the error and not exit the program.

EDIT: You can also override error globally, if you want, but that might lead to unexpected results if something goes terribly wrong somewhere else (code that you didn't write yourself) and the program continues nonetheless.

You'd be better off with a construct like this:

if os.getenv 'DEBUG' then
  my_error = function()
    -- what I explained above
  end
else
  my_error = error
end

and just use my_error in all the places where you'd usually use error.

Upvotes: 3

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