Comments for page "A case for unstructured programming"

(no title)

Sat, 01 Aug 2015 17:13:26 +0000

Indentation fixed.

As for the question, I would use goto. It's much more readble than do/break/while(0) construct.

(no title)

Sat, 01 Aug 2015 17:11:13 +0000

Most of serious C code uses goto for error handling. I wouldn't worry much about being seen as a heretic by C++/Java people. Just tell them to check the C best practice.

(no title)

Sat, 01 Aug 2015 17:05:10 +0000

In particular I often have code that looks like this:

 if (obviously_no_result(request)) return null; calculation = check_something(request); if (calculation_shows_no_result(calculation)) return null; if (more_expensive_check_shows_no_result(calculation)) return null; full_calculation = expensive_full_check(request, calculation); if (!full_calculation) return null; result = get_result_structure(request, full_calculation); notify_hooks(result); return result;

i.e. the fact that additional calculations are needed between ifs means that else-if cannot be used, and the performance hit of putting all calculations up front is unacceptable when most calls will (intentionally) fail.

I've used this style for 20 years for efficiency and clarity. It is much more clear than 'only return once' style code. When I wrote a textbook with an example using this style it garnered a bad Amazon review from someone who complained it showed I was a terrible programmer, because I didn't follow 'best practice' as taught in their Java course. Not that I'm bitter, or anything…

The complaint is that, if I need to do something for every failure (like adding a log, say), it is easy to forget a place to add it. I'm increasingly thinking that goto is actually a pretty good solution, and labels are a form of documentation. Though my need to be seen as non heretical probably stops me from using it in anger:

 if (obviously_no_result(request)) goto no_result; calculation = check_something(request); if (calculation_shows_no_result(calculation)) goto no_result; if (more_expensive_check_shows_no_result(calculation)) goto no_result; full_calculation = expensive_full_check(request, calculation); if (!full_calculation) goto no_result; valid_result: result = get_result_structure(request, full_calculation); notify_hooks(result); return result; no_result: notify_error_hooks(request); return null;

(no title)

Thu, 23 Jul 2015 23:30:22 +0000

Sorry about the broken formatting, I didn't realize the indentation will collapse and I can't edit the post now. INDENT(1) is your friend… ;-)

(no title)

Thu, 23 Jul 2015 23:27:14 +0000

if do_stuff*() require a lot of surrounding context so cannot easily be factored out into a seperate function, would you advocate for using break over nested if()s?

 void foo(void) { setup_do_stuff_context(); do { if(condition1()) { do_stuff1(); break; } if(condition2()) { do_stuff2(); break; } if(condition3()) { do_stuff3(); break; } do_stuff4(); } while (0); teardown_do_stuff_context(); }

(no title)

Sat, 18 Jul 2015 13:16:15 +0000

Yeah, I often do the same.

However, more often flattening the structure is harder to achieve and one must actually think and experiment with moving pieces around.

(no title)

Sat, 18 Jul 2015 12:29:29 +0000

Beautiful reference!

I often use early return as illustrated following the principal of avoiding deep nesting. One of my favorite refactorings is adding return to a the first branch and removing the matching else with an outdent of its block.

(no title)

Sat, 18 Jul 2015 07:58:40 +0000

I've showed the simplest possible example. If you look at real-world examples you'll find out that lot of stuff out there cannot be nicified in this way.

(no title)

Sat, 18 Jul 2015 07:52:15 +0000

Well, the way you presented your "ugly" code is a bit convoluted. You would probably write it like this:

 void foo(void) { if (condition1()) do_stuff1(); else if (condition2()) do_stuff2(); else if (condition3()) do_stuff3(); else do_stuff4(); }

(no title)

Sat, 18 Jul 2015 07:40:59 +0000

One of the codebases I had been working on pushed this style even further:

 void foo(void) { if (condition1()) DO_RETURN(do_stuff1()); if (condition2()) DO_RETURN(do_stuff2()); do_stuff3(); }