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Date: Tue, 24 Sep 2013 14:12:56 +0200
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To: David Soria Parra <dsp@php.net>
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Subject: Re: [PHP-DEV] RFC: Anonymous Classes
From: linepogl@gmail.com (Lazare Inepologlou)

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2013/9/24 David Soria Parra <dsp@php.net>

> Lazare Inepologlou <linepogl@gmail.com> schrieb:
> > I use anonymous classes very frequently in Java and in C#, and I would
> say
> > that they are quite useful. However the examples given in the RFC are
> > really bad ones. Why on earth would you need a constructor for an
> anonymous
> > class? Anonymous classes are used to implement quickly some interface.
> > Frankly, constructors are not part of any interface. Besides a
> constructor
> > is totally useless in an anonymous class as it will never be called aft=
er
> > the object is created.
>
> The need for anonymous classes in Java mostly comes from implementing
> interfaces on demand due to the lack of lamdas and the requirements of
> a strongly typed language. PHP has lambdas and it doesn't require you
> to match typing. Therefore I think the preferred way for most of the
> use cases is to use a lambda or if a bigger implementation is necessary,
> to give it a name. Due to namespacing you don't pollute the global scope
> anyway. Therefore I don't see much reason left as to why add anonymous
> classes and I really have a hard time finding a use case, except for tryi=
ng
> to write PHP as you would write Java (which most likely is a bad idea).
>
>
There are many use cases where anonymous classes are useful, even in the
presence of lambdas. I use them quite often when dealing with graphical
interfaces and templates. Here is an example:

abstract class MyFancyHtmlListView extends UI {
  protected function IsHeaderVisible(){ return true; }
  protected function GetListItemMenu(){ return null; }
  protected function OnItemClick( $item ){ }
  protected abstract function RenderListItem( $item );
  public function Render(){
    // echo ...
  }
}

With anonymous classes we could do something like this:

<?=3D new MyFancyHtmlListView(){
  protected function IsHeaderVisible(){
    return false;
  }
  protected function RenderListItem( $item ){
    // echo ...
  }
} ?>

The biggest advantage is that a missing RenderListItem could be statically
verified.

It is just a pattern that follows a different way of thinking: Instead of
having a list of parameters (including lambdas), we have standard methods
that take advantage of all the nice properties of OOP such as abstraction,
inheritance and polymorphism.




Lazare INEPOLOGLOU
Ing=C3=A9nieur Logiciel

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