Php sub-methods

Question

I've used php enough to be quite comfortable with it, but recently I've been looking through some MVC frameworks to try and understand how they work, and I've come across a syntax and data structure which I haven't encountered before:

function view($id)   
   {   
       $this->Note->id = $id;   
   }

What is the ->id section of this code? Is this a sub-method based off it's parent method? If so, how do I go about writing code to create such a structure? (ie. creating the structure from scratch, not using an existing framework like the above example from cakephp).

possible duplicate of [Absolutely basic PHP question about the "-> " syntax](http://stackoverflow.com/questions/4502587/absolutely-basic-php-question-about-the-syntax) — Gordon, Feb 11 '11 at 17:01
*(related)* [Reference: What does this symbol mean in PHP](http://stackoverflow.com/questions/3737139/reference-what-does-this-symbol-mean-in-php) — Gordon, Feb 11 '11 at 17:02
This would be a method in a class. See http://www.php.net/manual/en/language.oop5.basic.php — Nabab, Feb 11 '11 at 17:02
It essentially means that $this->Note is itself an object with the proprety $id. — Joe Green, Feb 11 '11 at 17:06

score 3 · Accepted Answer · answered Feb 11 '11 at 17:14

3

The following code demonstrates how one could arrive at the structure you described.

<?php

class Note
{
    public $id = 42;
}

class MyClass
{
    public function __construct() {
        // instance of 'Note' as a property of 'MyClass'
        $this->Note = new Note();
    }

    public function test() {
        printf("The \$id property in our instance of 'Note' is: %d\n",
            $this->Note->id);
    }
}

$mc = new MyClass();
$mc->test();
?>

answered Feb 11 '11 at 17:14

Jon Nalley

511
2
8

Shouldn't `MyClass` have `var $Note` before the constructor? – gen_Eric Feb 11 '11 at 17:29
There is no requirement to declare instance properties, but you are right - it is probably "more correct". BTW, 'public' or 'private' is preferred over 'var'. See: http://php.net/manual/en/language.oop5.properties.php – Jon Nalley Feb 11 '11 at 17:57
you dont have to declare anything in php – dogmatic69 Feb 12 '11 at 02:19
@dogmatic69: That is an absolutely false statement. – netcoder Feb 12 '11 at 04:37

score 2 · Answer 2 · answered Feb 11 '11 at 17:05

2

Note is a property of $this and it's (current) value is an object with a property named id which gets assigned the value of $id.
If id was a method of the Note object, the line would read $this->Note->id($id);.

answered Feb 11 '11 at 17:05

rik

8,592
1
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score 1 · Answer 3 · answered Feb 11 '11 at 17:15

1

Another way to think about the construct is considering

 $this->Note->id = $id;

similar to

 $this["Note"]["id"] = $id;

Which would actually be equivalent if both objects ($this and subobject Note) were based on ArrayAccess.

answered Feb 11 '11 at 17:15

mario

144,265
20
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Php sub-methods

3 Answers3