How do you write this down?

IceCave · 2015-07-18T23:16:23

Let's say we have an algorithm that differs in logical execution by the fact if one variable is negative or positive. Example code with bloat code and kind of non-bloat code if( v > 0 ) { while( x < 0 ) { x++; y+=x; // keeps the same y--; z+=y; // keeps the same z++; if( doA() ) doB(); } } else { while( x > 0 ) { x--; y+=x; // keeps the same y++; z+=y; // keeps the same z--; if( doB() ) doA(); } } while( v > 0 ? x < 0 : x > 0 ) { x += v > 0 ? 1 : -1; y+=x; // keeps the same y += v > 0 ? -1 : 1; z+=y; // keeps the same z += v > 0 ? 1 : -1; if( v > 0 ) { if( doA() ) doB(); } else { if( doB() ) doA(); } } Do you prefer the bloat code variant (#1) for performance reasons by avoiding many unusual checks or the shorter variant (which kind of is also bloat code but more easily maintainable) (#2) with lots of if-clauses or a third variant? I come across such structures very often when it comes to heuristics in mathematical functions, avoiding calculations effectively. I started thinking heavily about it after I found a method that implements a "simple" vector analysis function (which takes maybe ~5lines of code) in a performance critical environment but crowded with heuristics to avoid possible unnecessary calculations (Example #1), oh and me sitting in front of it trying to understand it and find a bug that "maybe" is hidden between ~82 lines of repeating unreadable code. On the one hand I thought: This is really great, it narrows down the number of possible solutions by just differentiating if this vector is negative or positive on all three axis. On the other hand I thought: Who wrote this? Who had so much time doing this and how am I supposed to maintain this? However, my most important thought was: Is there any way to write this code way easier? I just wanted to hear your thoughts because this keeps me thinking, even if your thought is that I should stop thinking about it Thanks With Best Regards IceCave

Coding Horrors Community

Started by IceCave July 16, 2015 02:32 PM

20 comments, last by Sik_the_hedgehog 8 years, 9 months ago

Polama

1,105

July 17, 2015 08:31 PM

In the unlikely situtation doA() and doB() don't use or change x,y,z there's always:


for(i = 0; i < x; i++)
{
    if(v > 0 && doA())
    {
        doB()
    }
    else if(v <= 0 && doB())
    {
        doA()
    }
}

z += ((x^2 + x)/2) + y*x + x
y += x + (x^2 + x)/2
x = 0

Sik_the_hedgehog

3,003

July 18, 2015 11:16 PM

I think the idea is that you take the comparison out of the loop for performance reasons, though.

...actually that's a good question: assuming the loop is short enough, would the compiler optimize out the comparison within the loop as two separate loops altogether? This would solve the clarity issue completely (simply write it once and let the compiler sort it out as needed).

Don't pay much attention to "the hedgehog" in my nick, it's just because "Sik" was already taken =/ By the way, Sik is pronounced like seek, not like sick.

How do you write this down?

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How do you write this down?

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