PHP: Functionally obtaining array of properties from object - php

Question

I have a simple class like this:
class MyClass {
public $color = 'red';
public $width = 200;
public $height = 100;
public function getValues(array $properties) {
return array_map(function($property) {
return $this->$property;
}, $properties);
}
}
I would like to do the following:
$values = (new MyClass)->getValues(['width', 'height']);
Where $values would end up containing this array: [200, 100].
The following example above works perfectly fine, so my question is:
How can we simplify the getValues() method? Surely there is a simpler way to achieve this?
Requirements:
It should be functional (no for/while loops). <- this criteria is met in my example
It should not use a callback function. <- this criteria is not met in my example

Answer 1

You could store your class-variables in an array and then use array_intersect_key() and array_flip() to achieve that. Here is an example.
class MyClass {
public $values = [
'color' => 'red',
'width' => '200',
'heigth' => '100'
];
public function getValues (array $properties) {
return array_intersect_key ($this -> values, array_flip ($properties));
}
//EDIT 2
public function set_value ($key, $value) {
$this -> values[$key] = $value;
}
}
//EDIT (thanks to mae)
It is also possible to generate an array of the class properties with ReflectionClass() and getProperties().
//EDIT (thanks to Nigel Ren)
Instead of Reflection it is possible to use get_object_vars() to achieve the same output.
class MyClass {
public $color = 'red';
public $width = '200';
public $heigth = '100';
public function getValues (array $properties) {
return array_intersect_key (get_object_vars ($this), array_flip ($properties));
}
}

Answer 2

Consider a new approach:
class MyClass
{
public $prop = array();
public function set($key, $value)
{
$this->prop[$key] = $value;
}
public function get($key)
{
return $this->prop[$key];
}
}
$o = new MyClass();
$o->set('color', 'blue');
$o->set('pi', 3.14);
$o->get('color'); // blue
$o->get('pi'); // 3.14