I would suggest checking out ONCLEANUP objects. They allow you to automatically run code on exit from a function (more specifically, when the ONCLEANUP object is cleared from memory). Loren from The MathWorks discusses this in one of her blog posts here. If you place your above code in a function, it might look something like this:
function data = load_line(filename) data = ; fid = fopen(filename); if fid == -1 error('Couldn''t open file'); end c = onCleanup(@()fclose(fid)); data = getl(fid); end
Even if the call to GETL throws an exception, the ONCLEANUP object will still be cleared from memory on return from the function load_line, thus ensuring the file gets closed.