avoiding if statements

Question

I was thinking about object oriented design today, and I was wondering if you should avoid if statements. My thought is that in any case where you require an if statement you ca

Answer 1

How do you decide which object's method to use without an if statement?

Answer 2

If-statements are pretty core to programming so, in short, you cannot sensibly avoid them.

However, a key goal in OOP--in fact, one of the "pillars"--is encapsulation. The old "encapsulate what varies" rule helps you remove those troublesome if and case statements where you are trying to account for every option in your object. A better solution to dealing with branches, special cases, etc. is to use something like the "Factory" design pattern (Abstract Factory or Factory Method--depending on needs, of course).

For example, rather than having your main code loop check which OS your using with if statements then branch to create GUI windows with different options for each OS, your main code would create an object from the factory, which use the OS to determine which OS-specific concrete object to make. In doing this you are taking the variations (and the long if-then-else clauses) out of your main code loop and letting the child objects handle it--so the next time you need to make a change such as supporting a new OS, you merely add a new class from the factory interface.

Answer 3

I agree with Vance that the IF is not good, because it increases the conditional complexity and should be avoided as possible.

Polymorphism is a totally viable solution at condition it's used to make sense and not to "Avoid If".

A side note that does not fit to your OOP requirements but the Data Oriented approach also tends to avoid the branching.

Answer 4

Explain how to implement the following without an if statement or ternary logic:

if ( x < 5 ) {
   x = 0
} else {
   print x;
}

Answer 5

Avoiding If Statement: There are many ways to do, one of them is below:

int i=0;
if(i==1)
{
//Statement1
}

if(i==2)
{
//Statement2
}

if(i==3)
{
//Statement3
}

if(i==4)
{
//Statement4
}

Using Dictionary and delegate:

delegate void GetStatement ();

Dictionary<int,GetStatement > valuesDic=new Dictionary<int,GetStatement >();

void GetStatement1()
{
//Statement1
}
void GetStatement2()
{
//Statement2
}
void GetStatement3()
{
//Statement3
}


void GetStatement4()
{
//Statement4
}

void LoadValues()
{
valuesDic.Add(1,GetStatement1);
valuesDic.Add(2,GetStatement2);
valuesDic.Add(3,GetStatement3);
valuesDic.Add(4,GetStatement4);

}

Replacing If Statement:

int i=0;
valuesDic[i].Invoke();

Answer 6

Surely some form of comparison needs to be made regardless of what you do? In the end ... sure you can avoid if statements but you'd be producing code that is IDENTICAL to the code using an if statement.

Someone correct me if im wrong but I can't think of a time where you could get any win form doing this.