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Generator::send

(PHP 5 >= 5.5.0, PHP 7)

Generator::send — 向生成器中传入一个值

说明

public Generator::send ( mixed $value ) : mixed

向生成器中传入一个值，并且当做 yield 表达式的结果，然后继续执行生成器。

如果当这个方法被调用时，生成器不在 yield 表达式，那么在传入值之前，它会先运行到第一个 yield 表达式。As such it is not necessary to "prime" PHP generators with a Generator::next() call (like it is done in Python).

参数

value: 传入生成器的值。这个值将会被作为生成器当前所在的 yield 的返回值

返回值

返回生成的值。

范例

Example #1 用 Generator::send() 向生成器函数中传值


<?php
function printer() {
    while (true) {
        $string = yield;
        echo $string;
    }
}

$printer = printer();
$printer->send('Hello world!');
?>

以上例程会输出：

Hello world!

User Contributed Notes

anonymous at example dot com 21-Jun-2019 10:38


As of 7.3, the behavior of a generator in a foreach loop depends on whether or not it expects to receive data. Relevant if you are experiencing "skips".



<?php

class X implements IteratorAggregate {

    public function getIterator(){

        yield from [1,2,3,4,5];

    }

    public function getGenerator(){

        foreach ($this as $j => $each){

            echo "getGenerator(): yielding: {$j} => {$each}\n";

            $val = (yield $j => $each);

            yield; // ignore foreach's next()

            echo "getGenerator(): received: {$j} => {$val}\n";

        }

    }

}

$x = new X;



foreach ($x as $i => $val){

    echo "getIterator(): {$i} => {$val}\n";

}

echo "\n";



$gen = $x->getGenerator();

foreach ($gen as $j => $val){

    echo "getGenerator(): sending:  {$j} => {$val}\n";

    $gen->send($val);

}

?>



getIterator(): 0 => 1

getIterator(): 1 => 2

getIterator(): 2 => 3

getIterator(): 3 => 4

getIterator(): 4 => 5



getGenerator(): yielding: 0 => 1

getGenerator(): sending:  0 => 1

getGenerator(): received: 0 => 1

getGenerator(): yielding: 1 => 2

getGenerator(): sending:  1 => 2

getGenerator(): received: 1 => 2

getGenerator(): yielding: 2 => 3

getGenerator(): sending:  2 => 3

getGenerator(): received: 2 => 3

getGenerator(): yielding: 3 => 4

getGenerator(): sending:  3 => 4

getGenerator(): received: 3 => 4

getGenerator(): yielding: 4 => 5

getGenerator(): sending:  4 => 5

getGenerator(): received: 4 => 5

kexianbin at diyism dot com 29-Sep-2015 06:47


an example:



$coroutine=call_user_func(create_function('', <<<'fun_code'

    echo "inner 1:\n";

    $rtn=(yield 'yield1');

    echo 'inner 2:';var_export($rtn);echo "\n";

    $rtn=(yield 'yield2');

    echo 'inner 3:';var_export($rtn);echo "\n";

    $rtn=(yield 'yield3');

    echo 'inner 4:';var_export($rtn);echo "\n";

fun_code

));

echo ":outer 1\n";                                       // :outer 1

var_export($coroutine->current());echo ":outer 2\n";     // inner 1:, 'yield1':outer 2

var_export($coroutine->current());echo ":outer 3\n";     // 'yield1':outer 3

var_export($coroutine->next());echo ":outer 4\n";        // inner 2:NULL, NULL:outer 4

var_export($coroutine->current());echo ":outer 5\n";     // 'yield2':outer 5

var_export($coroutine->send('jack'));echo ":outer 6\n";  // inner 3:'jack', 'yield3':outer 6

var_export($coroutine->current());echo ":outer 7\n";     // 'yield3':outer 7

var_export($coroutine->send('peter'));echo ":outer 8\n"; // inner 4:'peter', NULL:outer 8

sergei dot solomonov at gmail dot com 08-Oct-2013 06:30


<?php

function foo() {

    $string = yield;

    echo $string;

    for ($i = 1; $i <= 3; $i++) {

        yield $i;

    }

}



$generator = foo();

$generator->send('Hello world!');

foreach ($generator as $value) echo "$value\n";

?>



This code falls with the error:

PHP Fatal error:  Uncaught exception 'Exception' with message 'Cannot rewind a generator that was already run'.

foreach internally calls rewind, you should remember this!

sfroelich01 at sp dot gm dot ail dot am dot com 17-Jul-2013 12:11


Reading the example, it is a bit difficult to understand what exactly to do with this. The example below is a simple example of what you can do this.



<?php

function nums() {

    for ($i = 0; $i < 5; ++$i) {

                //get a value from the caller

        $cmd = (yield $i);

        

        if($cmd == 'stop')

            return;//exit the function

        }     

}



$gen = nums();

foreach($gen as $v)

{

    if($v == 3)//we are satisfied

        $gen->send('stop');

    

    echo "{$v}\n";

}



//Output

0

1

2

3

?>

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Generator::send

说明

参数

返回值

范例

User Contributed Notes

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