avoiding if statements

user_136659 0
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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 can simply create two objects that implement the same method. The two method implementations would simply be the two possible branches of the original if statement.

I realize that this seems extreme, but it seems as though you could try and argue it to some extent. Any thoughts on this?

EDIT

Wow that didn't take long. I suppose this is way too extreme. Is it possible to say though, that under OOP you should expect way less if statements?

SECOND EDIT

What about this: An object that determines its method implementation based on its attributes. That is to say you can implement someMethod() in two ways and specify some restrictions. At any point an object will route to the correct method implementation based on its properties. So in the case of if(x > 5) just have two methods that rely on the x attribute

if-statement oop
24 Answers

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();
user_13347100

You must understand what (x > 5) really mean. Assuming that x represents a number, then it basically "classifies" all numbers greater than five. So the code would look like this in a language with python syntax:

class Number(Object):

    # ... Number implementation code ... #

    def doSomething():
        self = 0
        return self

    def doSomethingElse():
        pass

class GreaterThan5(Number):
    def doSomething():
        print "I am " + self

    def doSomethingElse():
        print "I like turtles!"

Then we could run code like the following:

>>> type(3)
<class Number>
>>> type(3+3)
<class GreaterThan5>
>>> 3.doSomething()
0
>>> (3 + 3).doSomething()
I am 6
>>> (7 - 3).doSomethingElse()
>>>

The automatic type conversion here is important. As far as I am aware, none of the languages today allow you to mess with integers this much.

In the end, you can do in your code whatever. As long as the people reading it can understand immediately. So the polymorphic dispatch on integers or anything unordinary must have really good reasoning behind it.

user_92781830
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