Basic classes in React PHP
- Promise
- Represents result of deferred computation
- Deferred
- Represents a pending action which is resolved or rejection
- Returns single instance of promise
Method handling promises
- then()
- Takes two callbacks as arguments
- The first one is called only when the promise is resolved
- The second one is called only when it is rejected
- Each callback can return a modified value which is passed to the next operator
- done()
- Takes two callbacks as arguments
- Returns only null, so it doesn’t allow chaining
- Intended only to consume the result without modification
- otherwise()
- A handler that is called when the promise is rejected
- Or when the preceding then method throws an exception
- always()
- This is the cleanup method called when the method is either resolved or rejected
Each method returns a new promise, so we can chain them.
Using promises in PHP
Install React PHP promise library using Composer.
composer require react/promise