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Date: Tue, 17 Nov 2015 15:37:21 +0000
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Subject: Re: [PHP-DEV] Immutable modifier
From: ajf@ajf.me (Andrea Faulds)

Hi,

Rowan Collins wrote:
> Hi Andrea,
>
> Andrea Faulds wrote on 17/11/2015 01:47:
>> Larry Garfield wrote:
>>> The "everything in the constructor" is the problem.  That results in,
>>> essentially, an obscenely long function call that just happens to be
>>> named __construct().  If I wanted something that obscure and hard to
>>> work with I'd just use anonymous arrays. :-)
>>
>> Huh?
>>
>> "with" methods and __construct are not exclusive. In fact, you could
>> have a private constructor and only have "with" methods. Only allowing
>> assignment to properties in the constructor doesn't prevent having a
>> nice API: have your methods call the constructor.
>>
>> I don't see what you're getting at here.
>>
>
> Making the "with" methods wrap the constructor tidies the public API,
> but that (private) constructor needs to be just as complex as Larry said
> earlier - you've got to manually extract all the properties of one
> instance, and pass them as parameters to the other. Or, you could copy
> them one by one inside the body of the constructor, which comes to the
> same thing - lots of boilerplate.

Does it? You can write a five-line constructor which does what you need:

     private function __construct(array $properties) {
         foreach ($properties as $name => $value) {
             $this->{$name} = $value;
         }
     }

You can do changes like so:

     public function withName(string $name): self {
         return new self(array_merge((array)$this, [
             "name" => $name
         ]));
     }

Not much code, no?

Thanks.

-- 
Andrea Faulds
http://ajf.me/