On Aug 26, 2005, at 5:55 AM, Derick Rethans wrote:
I'm just arguing that the current way that setters and getters are
implemented is broken. Instead of keeping a broken behavior I would
like
to see it fixed.
Derick,
It is not broken its incomplete. PHP doesn't really have an
implementation of getters and setters. The __get and __set are really
just "property not defined" hooks, not getters and setters (accessor
methods).
If you take a look at a dynamic language that does does define a
standard for getters and setters, Key Value Coding in Objective C, you
will see what I mean. KVC defines a (complicated) search path for
looking up a property:
1. Search the receiver’s class for an accessor method whose name
matches the pattern -get<Key>, -<key>, or -is<Key>, in that order.
2. If no accessor is found, and the receiver’s class method
accessInstanceVariablesDirectly returns YES, the receiver is searched
for an instance variable whose name matches the pattern _<key>,
_is<Key>, <key>, or is<Key>, in that order.
3. If no appropriate accessor or instance variable is found,
valueForUndefinedKey: is invoked for the receiver, and the value is
returned.
ObjectiveC's valueForUndefinedKey is the same as PHP's __get. What php
lacks is the stage in the process that looks for accessor methods. In
current PHP:
1. Search the object for an instance variable <key>
2. If no instance variable is found, __get is invoked on the object and
the value returned.
I think where you are running into trouble with the property keyword is
that it is targeting the wrong stage in the property name search
process. It simply does not make sense to declare properties in the
class for the "undefined property" (__get) stage of the search process.
Right now, most people simulate accessor methods in user space using
__get and __set and if statements, case statements, introspection,
arrays, or a variety of other techniques.
If you want to improve this process and bring it into the engine, then
the place to do it is the property name search path. This is where
declared properties with accessor methods should be handled. An
accessor method check could be added either before or after the check
for the instance variable. A new keyword isn't necessary here, a
simple naming convention could suffice as in ObjectiveC. Reflection
could be made aware of the naming conventions, etc.
However, adding the stage before, as in ObjectiveC, seems unlikely to
gain much support here because of potential BC issues with method names
and performance concerns. (Although, some things will become faster,
some things will become slower.)
Adding the stage after also seems unlikely to gain much support here
because it can be simulated fairly well right now in user space using
the current __get mechanisms. (Which is exactly what we do on the WACT
project.)
I happen to think that a PHP standard for accessor methods would be a
good thing, but adding a stage to the search path is a hard sell.
Without adding a stage to the search path for property names, a
property keyword such as proposed makes little sense, the current
mechanisms are sufficient.
I understand the problem you're trying to solve, support the need for a
solution, but don't think this proposal solves the problem.
Ref:
http://developer.apple.com/documentation/Cocoa/Conceptual/
KeyValueCoding/index.html
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