Question

I often encounter a situation where I have to get an array of values that come from multiple objects. Let me clarify that with an fictional situation and some code.

Imagine I have created a class…

class MyObject {
    public $x = 0;
    public $y = 0;
}

I have an array of instances…

$instances = array(
    new Object,
    new Object,
    new Object
);

and I want to join all x properties as strings, devided with comma’s… I would have to use a loop…

$array = array();

foreach($instances as $instance) array_push($array, $instance->x);

$str = implode(',', $array); // holds an array of all x values

That would totally work, but I am very much against unnecessary loops and pro native implementations because I have a little obsession for performance – I dislike looping through huge arrays only to get a single property off every instance.

Is there a native way to get an array of property values from multiple objects? If so, how? If not, any idea why not?

Thanks in advance.

Answer 1

A simple easy way is to use array_map

class MyObject {
    public $x = 0;
    public $y = 0;
}

$instances = array(
        new MyObject,
        new MyObject,
        new MyObject
);


$str = implode(",",array_map(function($v){ return $v->x;},$instances));
echo $str ; 

Or array_reduce

$str = trim(array_reduce($instances, function($a,$b){ $a .= $b->x . "," ; return $a;}),",");
echo $str ;

The both would output

0,0,0

You can also modify your class to use __toString() Example

class MyObject {
    public $x = 0;
    public $y = 0;
    function __toString() {
        return $this->x . "," . $this->y;
    }
}

$instances = array(new MyObject(),new MyObject(),new MyObject());
echo implode("\n", $instances);

Output

0,0
0,0
0,0