glen/throwable-generator

ThrowableGenerator

1.1.0 2018-07-26 12:03 UTC

Requires

• php: ^7.1

Requires (Dev)

• phpunit/phpunit: ^7.2
• symfony/var-dumper: ^4.1

MIT

• Elan Ruusamäe

README

Generator wrapper for yield be sequential regardless of using Generator::throw.

From top level view, Generator::throw discards next value from generator, but it's not completely lost, but instead it becames return value of throw() method.

This is rather inconvenient if you want values be returned by yield.

<?php
 
function generator() {
  foreach (range(1, 6) as $x) {
    try {
      yield $x;
    } catch (Throwable $e) {
      echo " !! exception: {$e->getMessage()}\n";
    }
  }
}

$generator = generator();

foreach ($generator as $x) {
  echo "process: $x\n";
  if ($x % 2 === 0) {
    $generator->throw(new RuntimeException($x));
  }
}

The above code prints:

process: 1
process: 2
 !! exception: 2
process: 4
 !! exception: 4
process: 6
 !! exception: 6

i.e values 3 and 5 were "lost" by using throw. This library makes result to be:

process: 1
process: 2
 !! exception: 2
process: 3
process: 4
 !! exception: 4
process: 5
process: 6
 !! exception: 6

See question and discussion on stackoverflow post

To use this class, wrap your original generator with this class:

$generator = new ThrowableGenerator($generator);

Note: There is API change, throw() will return nothing instead of next value from generator.