Re: class attributes and __construct

Hello Ashely, I would initialize the variable when I'm defining it as there isn't much of a point of doing it in the constructor unless I'm having the value changed by a parameter. In my opinion: class House {

    public $roof = true;

} is the way to go. Fernando. On 15/04/2010 11:54, Ashley Sheridan wrote:

On Thu, 2010-04-15 at 07:42 -0700, Tommy Pham wrote:

Hi Ashley,

     
-----Original Message-----

From: Ashley Sheridan [mailto:ash@ashleysheridan.co.uk] Sent: Thursday, April 15, 2010 6:38 AM To: PHP General List Subject: [PHP] class attributes and __construct I think this is probably going to end up as one of those coders' preference type of things, but I was wondering what was considered the general best approach. When creating a class, you can define default values for the object in the class itself, and within the __construct function. Now, while I see the advantage to using __construct to set properties that might depend on a variable, what would be the best approach for any values that might likely remain at a default value and only ever change in a few rare circumstances? For example: class Person {

     public $right_handed = true;
       

I recommend setting it to private or protected instead of public to protect the integrity of the app. And add a get method/function to obtain the value.

     
     function __construct($name, $height)
     {
         $this->name = $name;
         $this-height = $height;
     }

     function set_hand($side)
     {
         if($side == 'left'
         {
             $this->right_handed = false;
         }
         else
         {
             $this->right_handed = true;
         }
     }

} Now, this is a simple example, but a value like $right_handed should only ever change if it's not the typical. As most people are right-handed it would make sense to set it to true and allow it to be changed to false as necessary. What I'm wonder is, where is the best place to set it to true, in the list of class properties at the top, or in the __construct() function? I know I could move it to __construct and give it a default value in the arguments list, but that brings it's own problems. What if the argument list grows too big, and which attribute would be deemed more important than another that you might want to override it without specifying every other? Is there a rule of thumb as to what belongs in __construct and what does not? Thanks, Ash http://www.ashleysheridan.co.uk

As for setting the default value in the construct, I recommend not to because should PHP support overloading later, you can then have another method/function to change its non-default value along with the initial parameters for the class. I use the constructor to set initial parameters for the class or initialize any class specific settings such as connection for DBAL. Regards, Tommy

Maybe my example wasn't the best, but I did mean that my public variable there was a value that should be initially set with the class initialisation I realise the differences between public, private and protected variables, that wasn't my question. What I wanted to know was if there was a convention about what specific properties should be set through the public $var = method and what should be left for the __construct function? For example, which would be better here (assuming a variable number of variables that might be set this way: class House {

     public $roof = true;

} class House {

     function __construct()
     {
         $this->roof = true;
     }

} Aside from the amount of typing (which isn't a serious consideration for me anyway) and assuming that such variable initialisation will not rely on variable input but will be fixed with the option of a class method to change the value later, what would be the preferred method and are there any caveats I'm unaware of right now (as I'm aware of none so far) to either method? Thanks, Ash http://www.ashleysheridan.co.uk