John Carmack's comment on Doom 3's code style

Post by johnbellone » Tue, Jan 15, 2013, 3:40 PM UTC

npsimons wrote: post #95

georgeorwell wrote: post #87

Earlier quoted context omitted.

It strikes me that your argument taken to the extreme is that everybody should program in assembly language because you can do anything, anytime, anywhere. Well, at least as far as control flow structures are concerned. Certainly C is preferable to C++ if you want simple and malleable code. Do you also prefer if-else to switch statements? (I'm not sure.) Do you like to use goto? (I doubt it.) Do you eschew the use of…

Not to mention that it's essential for initializing some constant variables; I have yet to find a better way to do: const int count = argc > 1 ? atoi(argv[1]) : 1000000; For quick test programs where I might want to change some number of iterations without having to recompile, but I also don't want to have to provide an argument every time I run it.

  const int kDefaultValue = 1000000;
  int value = kDefaultValue;
  if (argc > 1) {
    value = std::atoi(argv[1]);
  }
  const int count = value;

Post by dpark » Tue, Jan 15, 2013, 4:05 PM UTC

jaegerpicker wrote: post #186

dpark wrote: post #25

Earlier quoted context omitted.

void up_front_decls() { float some_var; int another_var; some_var = get_some_var(); do_some_calculations(some_var); maybe_something_else(&some_var); some_var = get_another_var(); do_some_other_calculations(another_var); blah_blah_already_broken(); } void as_needed_decls() { float some_var = get_some_var(); do_some_calculations(some_var); maybe_something_else(&some_var); int some_var = get_another_var(); // compile-ti…

Your up fornt example isn't a result of poor style it's the result of a bad programmer. Assigning the right values to the right variables is the most basic of programming concepts. Sure typo's and bugs happen, I've done it too but it's still a programmer error not style error.

Post by npsimons » Tue, Jan 15, 2013, 4:44 PM UTC

johnbellone wrote: post #191

npsimons wrote: post #95

Earlier quoted context omitted.

Not to mention that it's essential for initializing some constant variables; I have yet to find a better way to do: const int count = argc > 1 ? atoi(argv[1]) : 1000000; For quick test programs where I might want to change some number of iterations without having to recompile, but I also don't want to have to provide an argument every time I run it.

You're assuming that the first argument here is an integer value. For a single, one off, testing haress application I wouldn't worry too much about applying a full-blown semantic code style. Is there anything wrong with keeping the default value as a separate constant? const int kDefaultValue = 1000000; int value = kDefaultValue; if (argc > 1) { value = std::atoi(argv[1]); } const int count = value; Personally I much…

Post by tracker1 » Tue, Jan 15, 2013, 5:00 PM UTC

regularfry wrote: post #174

linhat wrote: post #69

Earlier quoted context omitted.

I really do not understand why they chose to do so. In my opinion, it does not improve readability at all, even worse, when the spacing between type and name gets big , your eyes need more work to figure out the correct line relations. Furthermore, this can generate horrible commits, for example: int x; int y; becomes: int x; int y; float z; after adding ONE single variable. But your commit will contain changes for t…

I do use vertical alignment, but that's not necessarily how I'd align the above lines. Assuming y and z are related, but x is not, I'd do them like this: int x int y float z I might add a blank line between x and y, too. If you do vertical alignment such that it emphasises semantic relations, you avoid commits that change more than they should, and it also helps draw your eye to relationships between variables.

    int   x
    int   y
    float z
    MyReallyLongTypeHere foo;

    var foo = (sometype)null;

Post by Too » Tue, Jan 15, 2013, 7:26 PM UTC

jblow wrote: post #51

Cushman wrote: post #50

Earlier quoted context omitted.

Bravo. That comparison makes worrying about vertical space seem ludicrous.

Ugh. I prefer the Carmack version. This example turns the code into something that appears more airy but in fact is much harder to understand due to extensive use of ? :. I find that one of my own major steps toward programming maturity happened when I stopped doing goofy things like this and started writing code that was as simple as possible to logically follow, and that was as un-special-cased as possible. (By thi…