rfc:generators

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rfc:generators [2012/09/01 17:22] – Change state to "Implemented" nikicrfc:generators [2012/12/23 23:44] – Add ::throw() method nikic
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     mixed send(mixed $value);     mixed send(mixed $value);
 +    mixed throw(Exception $exception);
 } }
 </code> </code>
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   * ''next'': Resumes the generator (unless the generator is already closed).   * ''next'': Resumes the generator (unless the generator is already closed).
   * ''send'': Sets the return value of the ''yield'' expression and resumes the generator (unless the generator is already closed). (More in the "Sending values" section.)   * ''send'': Sets the return value of the ''yield'' expression and resumes the generator (unless the generator is already closed). (More in the "Sending values" section.)
 +  * ''throw'': Throws an exception at the current suspension point in the generator. (More in the "Throwing into the generator" section.)
  
 ==== Yield syntax ==== ==== Yield syntax ====
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 $logger->send('Foo'); $logger->send('Foo');
 $logger->send('Bar'); $logger->send('Bar');
 +</code>
 +
 +==== Throwing into the generator ====
 +
 +Exceptions can be thrown into the generator using the ''Generator::throw()'' method. This will throw an exception in the generator's execution
 +context and then resume the generator. It is roughly equivalent to replacing the current ''yield'' expression with a ''throw'' statement and
 +resuming then. If the generator is already closed the exception will be thrown in the callers context instead (which is equivalent to replacing
 +the ''throw()'' call with a ''throw'' statement). The ''throw()'' method will return the next yielded value (if the exception is caught and no
 +other exception is thrown).
 +
 +An example of the functionality:
 +
 +<code php>
 +function gen() {
 +    echo "Foo\n";
 +    try {
 +        yield;
 +    } catch (Exception $e) {
 +        echo "Exception: {$e->getMessage()}\n";
 +    }
 +    echo "Bar\n";
 +}
 +
 +$gen = gen();
 +$gen->rewind();                     // echos "Foo"
 +$gen->throw(new Exception('Test')); // echos "Exception: Test"
 +                                    // and "Bar"
 </code> </code>
  
rfc/generators.txt · Last modified: 2017/09/22 13:28 by 127.0.0.1

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