goto bike shed

Posted Dec 27, 2014 17:44 UTC (Sat) by itvirta (guest, #49997)
In reply to: Re: you're wrong about the claim of needing a billion labels by ldo
Parent article: The "too small to fail" memory-allocation rule

> No! No GOTOs. They don’t nest easily, and they lead to spaghetti code. Look at the
> example code I linked above, and think how it would look with GOTOs all over the place.
> Avoid GOTOs!

> for(...) {
> if (PyErr_Occurred()) break;
> }
> if (PyErr_Occurred()) break;

I'm not sure I'd agree that breaking out of a loop just to test the same error condition,
to then only break out of another loop is any clearer than just jumping out directly.

Like someone mentioned, some other programming languages have dedicated constructs
(like exceptions) that can break out of multiple loops. It's not very different from what goto
was recommended for in this case.

(The thing with absolute rules is, that they absolutely forbid one from thinking. That usually
doesn't lead to anything good, so I would advise against it.)

> Fine. Try reworking the example I gave above, then. That has allocations nested up to three levels
> deep, as well as loops. See how well that works using GOTOs.

Reducing the nesting level and using a less space-hungry indenting style would be what I'd start with,
if I were to do this exercise for you.

Re: not sure I'd agree that breaking out of a loop just to test the same error condition

Posted Dec 27, 2014 20:46 UTC (Sat) by ldo (guest, #40946) [Link] (7 responses)

If you look at my code, you will see that each nested level has to do its own cleanup before propagating the error condition onwards. That is the whole point of the nesting.

Re: not sure I'd agree that breaking out of a loop just to test the same error condition

Posted Dec 27, 2014 20:57 UTC (Sat) by Cyberax (✭ supporter ✭, #52523) [Link] (1 responses)

Really? What cleanup is performed here: https://github.com/ldo/dvd_menu_animator/blob/master/spuh... ?

Or here: https://github.com/ldo/dvd_menu_animator/blob/master/spuh... ?

I actually don't see complicated cleanups anywhere in your code.

Re: What cleanup is performed here:

Posted Dec 27, 2014 21:36 UTC (Sat) by ldo (guest, #40946) [Link]

Try here or here.

Re: not sure I'd agree that breaking out of a loop just to test the same error condition

Posted Dec 28, 2014 3:27 UTC (Sun) by reubenhwk (guest, #75803) [Link] (4 responses)

>> If you look at my code, you will see that each nested level has to do its own cleanup before
>> propagating the error condition onwards. That is the whole point of the nesting.

Better yet, use a function for each of those nested levels. Worried about spaghetti code? Then factor out the nesting and call smaller functions with less looping and less nested resource management. Use the return value to propagate error conditions onward.

Re: Better yet, use a function for each of those nested levels.

Posted Dec 28, 2014 6:34 UTC (Sun) by ldo (guest, #40946) [Link] (3 responses)

Fine. Rewrite some suitably representative part of my code to show us an example of what you mean. There seems to be an enormous reluctance among you so-called programmers to actually do this. Perhaps because every time you try it, you get it wrong.

Re: Better yet, use a function for each of those nested levels.

Posted Dec 29, 2014 2:58 UTC (Mon) by reubenhwk (guest, #75803) [Link]

Perhaps we're on vacation and, even if we weren't, we have better things to do..

Re: Better yet, use a function for each of those nested levels.

Posted Dec 29, 2014 3:19 UTC (Mon) by bronson (subscriber, #4806) [Link] (1 responses)

Interesting use of the word "us". The royal we?

Re: Better yet, use a function for each of those nested levels.

Posted Dec 29, 2014 17:30 UTC (Mon) by nix (subscriber, #2304) [Link]

Probably the millions of lurkers who support him in email, using his fabulously readable coding style. I know I've encountered it everywhere! (... wait, that should be "nowhere".)

The argument from popularity is not a good one, but if something is not popular it is not terribly wise to imply that in fact it is.