How do you handle huge if-conditions?

Question

It\'s something that\'s bugged me in every language I\'ve used, I have an if statement but the conditional part has so many checks that I have to split it over multiple lines, u

Answer 1

Steve Mcconell's advice, from Code Complete: Use a multi-dimensional table. Each variable serves as an index to the table, and the if statement turns into a table lookup. For example if (size == 3 && weight > 70) translates into the table entry decision[size][weight_group]

Answer 2

Separate the condition in several booleans and then use a master boolean as the condition.

bool isOpaque = object.Alpha == 1.0f;
bool isDrawable = object.CanDraw && object.Layer == currentLayer;
bool isHidden = hideList.Find(object);

bool isVisible = isOpaque && isDrawable && ! isHidden;

if(isVisible)
{
    // ...
}

Better yet:

public bool IsVisible {
    get
    {
        bool isOpaque = object.Alpha == 1.0f;
        bool isDrawable = object.CanDraw && object.Layer == currentLayer;
        bool isHidden = hideList.Find(object);

        return isOpaque && isDrawable && ! isHidden;
    }
}

void Draw()
{
     if(IsVisible)
     {
         // ...
     }
}

Make sure you give your variables name that actualy indicate intention rather than function. This will greatly help the developer maintaining your code... it could be YOU!

Answer 3

As others have mentioned, I would analyze your conditionals to see if there's a way you can outsource it to other methods to increase readability.