10 criteria for knowing when to use object-oriented design

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Design is large,or is likely to become large

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When data is aggregated into obvIoUs structures,especially if there’s a lot of data in each aggregate

For instance,an IP address is not a good candidate: There’s only 4 bytes of information related to an IP address. An immigrant going through customs has a lot of data related to him,such as name,country of origin,luggage carried,destination,etc.

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When types of data form a natural hierarchy that lets us use inheritance.

Inheritance is one of the most powerful feature of OO,and the ability to use it is a flag.

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When operations on data varies on data type

GIFs and JPGs might have their cropping done differently,even though they’re both graphics.

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When it’s likely you’ll have to add data types later

OO gives you the room to expand in the future.

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When interactions between data is best shown by operators

Some relations are best shown by using operators,which can be overloaded.

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When implementation of components is likely to change,especially in the same program

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When the system design is already object-oriented

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When huge numbers of clients use your code

If your code will be distributed to others who will use it,a standard interface will make maintenence and safety easier.

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When you have a piece of data on which many different operations are applied

Graphics images,for instance,might be blurred,cropped,rotated,and adjusted.

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When the kinds of operations have standard names (check,process,etc)

Objects allow you to have a DB::check,ISBN::check,Shape::check,etc without having conflicts between the types of check.