Re: goto vs. return?

[John W. Eaton]

On 01/23/2016 05:27 PM, Rik wrote:
> According to the Appendix in the manual on Contributing to Octave,
>
> "Avoid comma expressions, labels and gotos, and explicit typecasts. If you need
> to typecast, use the modern C++ casting operators. In functions, minimize the
> number of return statements—use nested if statements if possible."
>
> Which do we dislike more: goto statements or return from the middle of a
> function?
>
> I ask because I count 134 uses of goto in liboctave.  I think most of these
> can be avoided now that the error_handler routine no longer returns.  The
> others could probably be removed if we used return rather than goto in the
> middle of a function.
>
> I personally dislike goto more than return and would remove it, but maybe
> there is a consensus in the other direction.

I'm not sure, but I think I typically chose goto when there might be 
some extra common processing to do before returning.

Also, I used to prefer the style

  if (condition_that_must_be_met_to_proceed_normally)
    {
       if (other_condition_that_must_be_obeyed)
         {
           // Do the thing we want to do.
         }
       else
         error ("nope, still not happening");
    }
  else
    error ("not happening");

because error did not throw an exception and because I like to read the 
conditions that must be met to succeed rather than those that can cause 
errors.  But this style is not perfect because it leads to lots of 
indentation for the part of the code that does the real work and, more 
importantly, it separates the call to error from the condition.  Now 
that error throws an exception, it seems fine to me to write

  if (! condition_that_must_be_met_to_proceed_normally)
    error ("not happening");

  if (! other_condition_that_must_be_obeyed)
    error ("nope, still not happening");

  // Do the thing we want to do.

Unfortunately, I don't think any particular style can guarantee clarity.

jwe