Question

I’m writing a matlab script where I’d like to know the name of the script which is one step up in the stack. The reason I need this is that I’m writing a helper script to be called to assert some basic facts about the workspace before engaging in heavier calculations, and the helper script should be able to give error messages when calling the calculation scripts.

I’ve tried using mfilename and dbstack, but I do not manage to get anything but the name of the helper script from them.

To explain further, I have the following scripts:

• verify_base_conditions: the helper script, called on one of the first lines in
• heavy_stuff_calculation and
• sweet_mother_of_algorithms.
• general_entry_point: a script where I gather common workflows in cells

I try to keep the entry point script as small as possible, and refactor heavier calculations (or anything that needs more than a few lines, really) into task-based, re-usable scripts. If I, from the entry point script, call sweet_mother_of_algorithms and the basic conditions for this script to run are not fulfilled, I want to see an error message like

Error: this_cool_var must be defined when running sweet_mother_of_algorithms
general_entry_point line 15

I tried using

error(['this_cool_var must be defined when running ' mdfilename])

and other similar constructs, but I couldn’t make the error message say anything but verify_base_conditions.

How do I find the name of the script running one level up in the stack?

(Note: I’m not interested in finding the script running at the bottom of the stack – that will almost always be general_entry_point. I’m just interested in getting the name of the script that called verify_base_conditions.)

Answer 1

dbstack should work for this. I think this is an analogous set-up to yours:

a.m:
  b;

b.m:
  c;

c.m:
  stack = dbstack;
  for i=1:3
    disp(stack(i));
  end

When I run a;, this prints out the whole stack, including b (which I think it was you want – the second-top item on the call stack.

Alternatively, although this probably gives exactly the same result, you could throw and catch an error and look at its stack:

c.m:
  try
    error('What is on the call stack?');
  catch e
    for i=1:3
      disp(e.stack(i));
    end
  end