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On Monday, 24 January 2022 at 11:23:38 UTC, rempas wrote:
>My point is if there is a true reason to implement "const" itself other than just protecting programmers that haven't read the documentation and are trying to modify a string literal?
There's this idea among some programmers that to prevent software bugs, we just need more well-trained / competent people, "like myself". This opinion tends to wane over time as you start writing those bugs you thought you'd never write.
I never understood the idea of people always including {} braces in if-statements and for-loops. The idea is to prevent this:
if (x)
y();
z();
What idiot would write something like that, z() is obviously not part of the if-statement anymore right? One day I had a single-line for-loop body, and to fix an error I quickly added an import statement above it, pushing the for-loop body outside the for-loop scope. Oops.
Yesterday I wrote a bug like this:
void alphabeta(ref Field field, /*...*/) {
// (...)
Field fieldCopy = field;
field.modify(); // < should be fieldCopy.modify()
alphabeta(fieldCopy);
// (...)
}
I was debugging it and noticed that I might as well mark the field parameter const since it wasn't supposed to change. The next compile I immediately got an error pointing at the bug!
Usually I mark variables/functions as strict as possible as early as possible, const / scope / pure / @safe etc. I don't know how many bugs I would have written when I wouldn't do that, but it's also comforting knowing that I don't have to worry about accidentally breaking these properties I rely on when I modify a part of the code days or weeks later. Because that's how it gets you: sure, you can do these checks yourself the first time you write a function, but will you do them again every time you make a modification in the future? The compiler can, you likely won't.
That said, it can also be annoying marking all function parameters const appropriately to convince the compiler that you indeed don't modify a const variable. I've heard of C++ people applying a macro #define const to a remove all const from a const-correct codebase because they don't like dealing with it. If you don't think it's worth it, you can not mark parameters const if you also don't mark your variables const.
