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Date: Mon, 23 Feb 2004 16:42:18 -0500
To: Marcus Boerger <helly@php.net>
Cc: PHP Development <internals@lists.php.net>
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Subject: Re: [PHP-DEV] Re: Static weirdness..
From: fuhs@purdue.edu (Josh Fuhs)

Quoting Marcus Boerger <helly@php.net>:

> In fact it may be related. As i said before it is one of the ways to get to
> a class.
> 

The class is related to the object. The method is related to the class. Is the
method related to the object? It is not.

There are many indirect ways to get to a class. I'll try to illustrate with an
example.

Say that we introduce a new semantic rule that says you can call methods on
arrays. The behavior is to scan through the array for any object on which it can
call that method.

i.e. $array = array($object1, $object2, ...);

$array->method(); /* Calls method on all objects in array. */

Could that be useful to coders? Yes. Is it a good language element? I would
argue no because the array is not directly related to the method.

Quoting Hartmut Holzgraefe <hartmut@php.net>:

> So why? as i stated before the only difference between static and
> non-static member functions is that non-static members *may* change
> the state of an instance while static members definetly won't
> 
>  From a callers point of view it is not even important to know
> that one is calling a static member when invoking the member
> function over an object instance, so why shouldn't it be callable
> like that?
> 

With non-static methods, you KNOW that the object is required in order for the
method call to be valid. Thus the statement $object->nonStaticMethod() includes
all of the information required for execution and no more.


I agree that it's logically safe to continue with the current semantics, but it
introduces a few maintenance headaches.

When reading through code, it helps to be able to know exactly what is being
affected without having to refer to any documentation or code. I agree that
reading documentation is important, but if it's not necessary, then it shouldn't
need to be done.

Consider the case where an object needs to be altered/removed from a solution
for one reason or another. Each place where a static method call is made from
that object has to be examined (i.e. refer to documentation). Depending on the
project, the number of these could be very large, whereas simply indicating the
class directly would alleviate that extra work. It adds virtually no extra work
for the original coder, since they are probably familiar with the objects they
are manipulating.

This is similar to the excessive use of global variables. I've had to maintain
software where the original author thought it best to use global variables as
function parameters. Doing so relates the parameter to the whole of the global
scope. This makes code maintenance a huge pain. Had the minimal relation been
used, this coder simply would have added a few more parameters to that
function's parameter list. Granted, that's much more of a pain than the static
methods, but the idea is similar.

So I guess my message is minimalism.


I am completely in favor of a 

$className::...

syntax. It is consistent with the 

$object->$elementName and
$functionName() 

syntaxes which I consider to be very strong points for PHP.

Also, if the 

$object->staticMethod()

scheme is to persist, for the sake of consistency, it would be nice to see 

$object->staticMember and
$object->CONSTANT

This is kind of part of my argument against $object->staticMethod() because I
imagine those would also create some headaches.

Josh