Re: php 5 classes: public, protected and private

Tony Marston wrote:
"Jerry Stuckle" <jstucklex@xxxxxxxxxxxxx> wrote in message news:Ib6dna_BtYQSifbYnZ2dnUVZ_sSdnZ2d@xxxxxxxxxxxxxx

jopperdepopper wrote:

You should read "can be accessed everywhere".

Private members can be accessed by members of the class only.
Protected members can be accessed by members of the class or a derived
class.
Public members can be accessed by anyone, including other classes,
functions and any other code.



Thanks Jerry. I'm trying to make a bit of sense of the php 5 approach
to classes, and so far having a hard time. I fail to see the 'why'
behind the 'public, protected and private' and stuff like abstraction,
interfaces and whatnot.


Intefaces are not necessary in PHP. Once you have defined a method it is a total waste to time to also define an interface. Interfaces are a "fix" in those languages as a means of dealing with optional arguments and statyic typing. PHP has ifferent ways of dealing with bth of these, therefore interfaces serve no useful purpose.


Ah, the great Tony Marston is back to trolling again.

Wrong. In OO terms, the interface is the way to interact with the object. It consists of all public members - both methods (functions, in PHP) and variables. And for derived classes, the base class adds protected members.

A PHP interface is something entirely different.


Feels like things are being over-complicated
somehow... or it's just my being inexperienced on this...

Any other reading material on this suggested, someone?


Look for some good books on OO theory and design.

Two of the concepts in OO are 'encapsulation' and 'methods'.

Encapsulation means the internals of an object are managed only by that object and are not available to anyone else. In PHP these are private members.


Wrong. Encapsulation means that the data and the functions which operate on that data are contained (encapsulated) within a single object. While the methods (functions) thenselves may be visible the code behind those methods (i.e. the implementaton behind those methods) is not. Encapslation is NOT about hiding information, it is about hiding the implementation. It is not necessary to use public/private/protected on any methods or properties. It does not add any functionality, it merely creates restrictions which often get in the way.


Wrong again, Tony. Encapsulation means internal representations of the object are not visible outside of the class. Just like the base & mantissa are not visible outside of a floating point number.


Methods are implemented as functions in PHP. They operate on the object.


That's one thing you got right.


More than you got right. Go crawl back into your hole and don't come out again until you know what you're talking about.

--
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Jerry Stuckle
JDS Computer Training Corp.
jstucklex@xxxxxxxxxxxxx
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  • Re: php 5 classes: public, protected and private
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