How to yield value with the key?

Question

How to set the key for yielded value? Can the generator have the key as well as array does?

I can easily name keys when returning arrays. It's very useful for PhpUnit dataProviders:

$array = [
    'key' => ['value',1,2,3],
    'here' => ['a',4,5,6],
    'there' => ['b',7,8,9],
];

foreach( $array as $key => $value ){
    echo $key."\t=>\t".var_export($value, true)."\n\n\n";
}

but can I do the same using generators?

e.g., how to change the following code?:

function hi()
{
    yield ['value',1,2,3];
    yield ['a',4,5,6];
    yield ['b',7,8,9];
}
$array = hi();
foreach( $array as $key => $value ){
    echo $key."\t=>\t".var_export($value, true)."\n\n\n";
}

Currently, the output is:

0   =>  array (
  0 => 'value',
  1 => 1,
  2 => 2,
  3 => 3,
)


1   =>  array (
  0 => 'a',
  1 => 4,
  2 => 5,
  3 => 6,
)


2   =>  array (
  0 => 'b',
  1 => 7,
  2 => 8,
  3 => 9,
)

How can I set the mindful keys for yielded values?

Answer 1

It is easy, yield has documented ability to use keys: https://www.php.net/manual/en/language.generators.syntax.php

function hi()
{
    yield 'key' => ['value',1,2,3];
    yield 'here' => ['a',4,5,6];
    yield 'there' => ['b',7,8,9];
}
$array = hi();
foreach( $array as $key => $value ){
    echo $key."\t=>\t".var_export($value, true)."\n\n\n";
}

The output will have keys, as well as an array does:

key =>  [
  0 => 'value',
  1 => 1,
  2 => 2,
  3 => 3,
]


here    =>  [
  0 => 'a',
  1 => 4,
  2 => 5,
  3 => 6,
]


there   =>  [
  0 => 'b',
  1 => 7,
  2 => 8,
  3 => 9,
]

Answer 2

Here is a sample how to use yeald keys as title explaining phpUnit test cases in data provider

<?php

use PHPUnit\Framework\TestCase;

class SomeDataProviderTest extends TestCase
{
    private SomeClass $someClass;

    protected function setUp(): void
    {
        parent::setUp();
        $this->someClass = new SomeClass();
    }

    /**
     * @dataProvider SomeDataProvider
     */
    public function testSomeMethod(string $expected, int $param1, int $param2, int $param3): void
    {
        $result = $this->someClass->someMethod($param1, $param2, $param3);
        $this->assertEquals($expected, $result);
    }

    public function SomeDataProvider(): \Generator
    {
        yield 'test case 1 explanation'     => ['value', 1, 2, 3];
        yield 'test case 2 title'           => ['a', 4, 5, 6];
        yield 'test case 3 for extra cases' => ['b', 7, 8, 9];
    }
}