PHP 7: Real World Application Development

Writing your own iterator using generators

In the preceding set of recipes we demonstrated the use of iterators provided in the PHP 7 SPL. But what if this set doesn't provide you with what is needed for a given project? One solution would be to develop a function that, instead of building an array that is then returned, uses the yield keyword to return values progressively by way of iteration. Such a function is referred to as a generator. In fact, in the background, the PHP engine will automatically convert your function into a special built-in class called Generator.

There are several advantages to this approach. The main benefit is seen when you have a large container to traverse (that is, parsing a massive file). The traditional approach has ...