According to the PHP in Action blog, public constructors can be hazardous to your (application's) health and should be replaced.

Everybody who writes object-oriented code knows about constructors. You need them so the program knows how to instantiate objects, right? And you especially need them when a lot of things have to be done while instantiating an object. [...] So why would I be skeptical of public constructors?

The solution, as he sees it, is to make a "constructor" that's actually called statically with parameters that returns an instance of the class it's in as well as performing the action. He argues that this can help make the code much more readable for some types of method calls.

On PHPBuilder.com today, there's a new tutorial that takes a beginning look at PHP5's class inheritance model.

There are many benefits of inheritance with PHP, the most common is simplifying and reducing instances of redundant code. Class inheritance may sound complicated, but think of it this way. Consider a tree. A tree is made up of many parts, such as the roots that reside in the ground, the trunk, bark, branches, leaves, etc. Essentially inheritance is a connection between a child and its parent.

They choose to go with a "car" illustration instead and show how a child of the Product class (Car) can access the private properties of the parent. They also include an example of it in action with a bit of HTML output.

Tobias Schlitt has posted a handy tip about using the Reflection API in PHP5 - specifically its accessing of private properties in a class.

I recently stumbled over reflecting private properties in PHP again. As you might know, this was not possible until now and if you tried this [code] PHP thanked it to you with this [error that is cannot access a non-public member].

He notes that, while the behaviour is correct, it still makes things like metaprogramming impossible. So, what's a developer to do? Patch it of course! Tobias and Derick Rethans persuaded two other developers (Derick and Marcus Borger) to include a patch that allows the Reflection API to see these private variables.

To make it work, you have to use the setAccessible method on the Reflection object to set which of the properties you want to be able to get at.

From CodeSnipers.com today, there's a new post with their look at objects in PHP5 - how they work, how they're different from in PHP4, and some code to show their use.

After a brief few weeks studying Perl and its nuances I'm going to take a look at PHP5 Objects.

One of the annoying things with object in PHP 4 was you had to use a lot of references, you know, that funny & symbol. No longer needed in PHP 5 because you use "Object Handles" perhaps similar to a file handler you when fopen a file. Also available now are access modifiers "public/protected/package" and interface implementation. I can hear the beer mugs of java programmers being raised in celebration to this one. Also new to PHP 5 are real constructors and destroy methods. There are many more features, but lets see some code.

There are code examples that show some of the new keywords (private, public, etc) that the object structure uses, as well as how you can use them. They link to the PDF of Power PHP 5 Programming for a good place to start...