Interface vs abstract class vs trait in PHP - Quick Revision & Key Differences

Recall & Review

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What is an interface in PHP?

An interface defines a contract with method signatures but no method bodies. Classes that implement the interface must provide the method implementations.

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What is an abstract class in PHP?

An abstract class can have both method signatures (abstract methods) and method bodies. It cannot be instantiated directly and is meant to be extended by other classes.

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What is a trait in PHP?

A trait is a reusable set of methods that can be included in multiple classes to share functionality without using inheritance.

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Can a PHP class implement multiple interfaces?

Yes, a PHP class can implement multiple interfaces, allowing it to follow multiple contracts.

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Can a PHP class use multiple traits?

Yes, a PHP class can use multiple traits to include different sets of reusable methods.

Which of the following can contain method implementations in PHP?

A Both B and C

B Abstract class

C Trait

D Interface

Abstract classes and traits can contain method implementations, while interfaces only declare method signatures.

Can a PHP interface have properties?

A Only if declared public

B Yes, with default values

C Yes, but only static properties

D No, interfaces cannot have properties

Interfaces cannot have properties; they only declare method signatures.

Which keyword is used to include a trait in a PHP class?

A implements

B extends

C use

D include

The 'use' keyword is used inside a class to include a trait.

Can a PHP class extend multiple abstract classes?

A No, PHP supports only single inheritance

B Yes, but only if abstract classes implement interfaces

C Yes, PHP supports multiple inheritance

D Only if using traits

PHP supports only single inheritance, so a class can extend only one abstract class.

What is the main purpose of traits in PHP?

A To define method signatures

B To share reusable code between classes

C To enforce class contracts

D To replace interfaces

Traits allow sharing reusable methods across classes without using inheritance.

Explain the differences between interfaces, abstract classes, and traits in PHP.

Think about what each one can contain and how they are used in classes.

When would you choose to use a trait instead of an abstract class or interface in PHP?

Consider code reuse and inheritance limitations.