Hi Ashley,

> -----Original Message-----
> From: Ashley Sheridan [mailto:a...@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.


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