Welcome to the Treehouse Community

Want to collaborate on code errors? Have bugs you need feedback on? Looking for an extra set of eyes on your latest project? Get support with fellow developers, designers, and programmers of all backgrounds and skill levels here with the Treehouse Community! While you're at it, check out some resources Treehouse students have shared here.

Looking to learn something new?

Treehouse offers a seven day free trial for new students. Get access to thousands of hours of content and join thousands of Treehouse students and alumni in the community today.

Start your free trial

PHP Designing Interfaces in PHP Using Interfaces Code to Multiple Interfaces

Jonathan Healy
Jonathan Healy
21,601 Points
Posted by Jonathan Healy
Jonathan Healy
21,601 Points

Can someone explain why we construct the RepositoryInterface in the Collection class opposed to implementing it?

I am unclear on the purpose of introducing the Repository Interface, and it's purpose there, inside of the constructor function of the Collection class.

Does this serve a different purpose as opposed to implementing it as we are with the Iterator and Countable interface?

1 Answer

Shoko Ishigaki
Shoko Ishigaki
21,826 Points
Shoko Ishigaki
Shoko Ishigaki
21,826 Points

In collection class, we have property called repo which is type "RepositoryInterface" (or class implementing RepositoryInterface). Inside constructor, we initialise the repo and then use that repo's function. Hope this helps.

Jonathan Healy
Jonathan Healy
21,601 Points
Jonathan Healy
Jonathan Healy
21,601 Points

That makes sense thank you for your assistance!