Why is this Getter and Setter behaving like this?
I recently came across this code question and am very unclear as to why it is producing these results.
Class Magic {
public $a ="A";
protected $b = array( "a"=>"A", "b"=>"B", "c"=>"C");
protected $c = array(1,2,3);
public function __get($v ) {
echo "$v,";
return $this->b[$v]; //internal so fine with protected.
}
public function __set($var, $val ) {
echo "$var: $val,";
$this->$var = $val;
}
}
$m = new Magic();
//1
//echo $m->a;
//prints A
//2
//echo $m->a;
//echo $m->b;
//prints Ab, B
//3
//echo $m->a.",," . $m->b;
//prints b,A,,B
I can not understand the behaviour for number 3. If somebody could explain I would be very appreciative as I can't find any answers anywhere on this behaviour.
I understand access modifiers and property visibility but I must have some gaps as not sure why 'b' is printing first as the getter calling the protected property is allowed to do so.
Additionally I would have thought 'A' would have printed first (like 1 and 2).
Find it strange why it behaves differently when it echoes both 'a' and 'b' at same time.
The only thing I can think is with echo
-With the comma version, each argument is evaluated and echoed in turn
-The dot version is different, it has to be fully evaluated before it can be echoed as requested.
But not sure (how does it evaluate?).
Thanks
It's because of the echo in __get method. If you call echo $m->a.",," . $m->b; echo $m->a.",," . $m->b; than first the functions inside statement get called. So the echo in __get will be first called.
That has nothing to do with PHP OOP per say but with the order of evaluation of operands:
echo ($m->a . ",," . $m->b);
is a concatenation of 3 operands:
So by the time the 3 operands have been concatenated into one string "A,,B", the program has already echo-ed "b,". Then the concatenated string is passed to YOUR command echo for output, hence final result: "b,A,,B"
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