Where to Use Inheritance and where to use Composition

I think you already know why object-oriented programing was invented and what problem it resolves.

It starts with class and object.

And please don't start by saying a class is a skeleton or blueprint blah blah... and object is an instance of that

blueprint blah blah. I don't like bookish language.

Simply, what we see is an object, for example, you are seeing a specific laptop of a specific brand (Dell suppose) is an object.

but what we say is a class. (Yes, we always say wrong.)

If I ask you what are you using to read this answer, you would reply "Laptop", not dell laptop.

But the laptop is a generic term, it has no meaning, a term which is in the air until you assign properties like brand, price, etc, and then it becomes a real thing called an object in the programming world.

Now, where there are objects there will be relationships, it can be any kind of relationship like is-a, uses, has-a etc.

Sachin is a human meaning sachin:human (sachin inheriting from human) that is inheritance.

Sachin: Human
{
}
Cat:Animal
{
}

Writer uses a pen to write on paper . This Means, Writer is dependent on a pen and a pen is dependent on Writer but both have their own existence also, which means the Writer can use any pen and a pen can be used by anyone. Both can easily live without each other. this is called Association.

public class writer
{
public void Write(Pen obj)
{
}
}

The painter uses multiple pencils for drawing, this is similar to the association but the only difference is that one of the dependent objects is multiple in quantity.

public class painter
{
public List penciples = new List();
}

The death relationship:- (Composition)

C#Corner is successful because of contributors. This means that both are dependent on each other and their life span will always be the same. Both will die in absence of one another.

public class website
{
public bool WebSiteSuccess()
{
if(contibutors>10k)
{
return true;
}
return false;
}
}
public class contributor
{
public bool isMVP()
{
if(publicRead>10k)
{
return true;
}
return false;
}
}

3 Replies

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Sachin Singh4y ago
I think you already know why object-oriented programing was invented and what problem it resolves.
It starts with class and object.
And please don't start by saying a class is a skeleton or blueprint blah blah... and object is an instance of that
blueprint blah blah. I don't like bookish language.

Simply, what we see is an object, for example, you are seeing a specific laptop of a specific brand (Dell suppose) is an object.
but what we say is a class. (Yes, we always say wrong.)
If I ask you what are you using to read this answer, you would reply "Laptop", not dell laptop.

But the laptop is a generic term, it has no meaning, a term which is in the air until you assign properties like brand, price, etc, and then it becomes a real thing called an object in the programming world.

Now, where there are objects there will be relationships, it can be any kind of relationship like is-a, uses, has-a etc.
Sachin is a human meaning sachin:human (sachin inheriting from human) that is inheritance.
Sachin: Human
{


}
Cat:Animal
{
}
Writer uses a pen to write on paper . This Means, Writer is dependent on a pen and a pen is dependent on Writer but both have their own existence also, which means the Writer can use any pen and a pen can be used by anyone. Both can easily live without each other. this is called Association.
public class writer
{

public void Write(Pen obj)
{

}

}
The painter uses multiple pencils for drawing, this is similar to the association but the only difference is that one of the dependent objects is multiple in quantity.
public class painter
{
public List penciples = new List();

}
The death relationship:- (Composition)
C#Corner is successful because of contributors. This means that both are dependent on each other and their life span will always be the same. Both will die in absence of one another.
public class website
{
public bool WebSiteSuccess()
{
  if(contibutors>10k)
{
return true;
}
return false;
}
}

public class contributor
{

public bool isMVP()
{
  if(publicRead>10k)
{
return true;
}
return false;
}

}
Ashwani Chaudhary4y ago
I already gone through with the link and its not a real world application scenario .Just explained the concept which is good one but i am looking a way where i can try and do a brainstorming on choosing on of them .....Inheritance or composition .

Actually Everyone explain the concepts but some of them hardly use a really world scanario which gives a real feel to choose and use and it really make a concept robust . Well thanks fot rply Rajankant .
Rajanikant Hawaldar4y ago
https://www.c-sharpcorner.com/UploadFile/ff2f08/inheritance-vs-composition/