PHP Calling a callback function from within Object method

Question

I am building a scheduler that will take a callback function and will execute that function a given amount of times, and in between a given amount of delay. Below is that the interface for what the functionality looks like.

Side note I am using the Laravel Framework;

public function testBasicTest()
{
    $count = 0;
    $schedule = new NodeScheduler();
    $schedule->retries(2)->delay(100000)->do(function() use ($count) {
        $count++;
    });
    $this->assertEquals($count === 1);
}

This is my test for this piece of functionality and as you can see i want count to equal 2 by the end of it.

My class looks like this;

class NodeScheduler
{
    protected $retries = 1;
    protected $milliseconds = 10000;

    public function __construct()
    {
        return $this;
    }

    public function retries($numberOfRetries)
    {
        $this->retries = $numberOfRetries;
        return $this;
    }

    public function delay($milliSeconds)
    {
        $this->milliSeconds = $milliSeconds;
        return $this;
    }

    public function do($callback)
    {
        for($i = 0; $i < $this->retries; $i++){
            $callback(); // <<<<<< How Do I Inject The $count Variable Here?
            usleep($this->milliseconds);
        }
        return;
    }
}

My test fails with:

Failed asserting that 2 matches expected 0.

Strangely I don't get $count is undefined.

I think i am close, any help greatly appreciated

I think you want to write $this->assertEquals(1, $count);

Arno
– Arno

2017-10-06 08:25:44 +00:00
Commented Oct 6, 2017 at 8:25 — Arno
– Arno, Commented Oct 6, 2017 at 8:25

rickdenhaan · Accepted Answer · 2017-10-06 08:35:03Z

3

When you use() a variable from the outer scope inside a function, this creates a copy of the variable into the function's inner scope (an exception is if you're use()ing an object).

If you want to import a variable from the outer scope and modify it, you'll need to pass it in by reference:

$schedule->retries(2)->delay(100000)->do(function() use (&$count) {
    $count++;
});

Edit: Also, what @Arno and @Oniyo pointed out: either use assertEquals(1, $count) or use assertTrue($count === 1)

answered Oct 6, 2017 at 8:35

rickdenhaan

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1 Comment

John Mack Over a year ago

I had no idea about the pass by reference, thank you very much

Oniya Daniel · Accepted Answer · 2017-10-06 08:34:40Z

0

I think you are doing two things wrong

Firstly: As @Arno pointed out,

$this->assertEquals($expected, $actual);

Secondly: From what I see in your code, the loop will run $this->retries's iterations. So, $this->assertEquals($expected, $actual) should be

$this->assertEquals(2, count);

Good luck man!

answered Oct 6, 2017 at 8:34

Oniya Daniel

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