When to use PHP interfaces?

[dado.d]

I've been working in various companies and I've seen different reasons for using PHP interfaces. I would like to hear your opinion, what do you think in which cases should we use PHP interfaces, the reason behind using interface?

[rproffitt]

I took a look at https://www.google.com/search?&q=When+to+use+PHP+interfaces and it seems to be well discussed.

Can you narrow down what you are looking for beyond the usual answer?

[dado.d]

I read most of that but it didn't give me the answer. Maybe I should ask: "How do I recognize whether I should use interface or not?"

[rproffitt]

The answer lies in what PHP Interfaces do for us. Another answer is you don't have to use it. Here's the paragraph that sums up why we would use it:

Interfaces allow you to define/create a common structure for your classes – to set a standard for objects. Interfaces solves the problem of single inheritance – they allow you to inject 'qualities' from multiple sources. Interfaces provide a flexible base/root structure that you don't get with classes.Aug 26, 2006 - https://www.killerphp.com/articles/php-interfaces/

Nothing forces you to do this. It's your choice but it could help if your code has grown unweildy.

[jeevanism]

You can implement multiple inheritance using interaces.

Example

Class Student implements AlumniInterface, SportsClubInterface, MusicClubInterface {

// say is each interface have methods like  findAlumniInMNC(), accestoGym(), accessToMusicInstruments()

}
// a object of the class student will have access to all of above methods
$john = new student();

[pritaeas]

"How do I recognize whether I should use interface or not?"

The most common usage of interfaces is when you find you need to create different (unrelated) classes to have similar required functionality.