IsA or HasA?

IsA or HasA?

When designing a class hierarchy, you may face a decision between inheritance (aka IsA ) vs. containment (aka HasA) relation. For instance, if you are designing a


class, and you already have the following classes implemented for you in some library:

 Dial, ElectricAppliance. 

It is quite obvious that your Radio should be derived from


However, it is not so obvious that


should also be derived from


. How to decide? You can check whether there is always a 1:1 relation between the two, e.g., do all radios have one and only one dial? You may realize that the answer is

See also  Redefining Energy Management: Advanced Solutions for Modern Buildings

About Our Editorial Process

At DevX, we’re dedicated to tech entrepreneurship. Our team closely follows industry shifts, new products, AI breakthroughs, technology trends, and funding announcements. Articles undergo thorough editing to ensure accuracy and clarity, reflecting DevX’s style and supporting entrepreneurs in the tech sphere.

See our full editorial policy.

About Our Journalist