Delegation

PHP 7 uses generators more universally. At this point, it should be mentioned that the yield operator will always work right-associatively in the future. Listing 8 demonstrates that generators no longer need to reside exclusively in loops but can also exist in generators themselves – "generator delegation" in technical jargon.

First, the code creates a generator object in lines 2-7 by calling an anonymous function and storing it in the $fibo1 variable. As usual, yield statements create the generator's return values. Line 5 obtains the return value from a second generator (line 9); the from keyword precedes the call.

The code from lines 14 to 16 uses a foreach loop to iterate in the normal way over the generator object. Line 15 outputs the first few Fibonacci numbers using the shell until it has received return values from all yield statements. PHP 7 generates another, final value using the return statement in line 6, which the getReturn() method in the last line gets from the generator object.

Conclusions

PHP 7 resolves many imperfections in the popular web language at the cost of losing downward compatibility. Even simpler PHP scripts could object to the new underpinnings.

However, PHP 7 is likely to be accepted widely if the performance doubles compared with the previous version 5.6, as the makers and some benchmarks [3] suggest it has. The type declarations in functions will also be useful because they force programmers to take more care.

Considering the other changes affecting standard functions, classes, and interfaces, it would definitely be a good idea for developers to read the PHP 7 documentation [2]. Despite these obstacles, the major release should confirm convictions of many web developers that PHP is the best tool for programming web applications on the server.