Re: Using a Resource as a Class Property

Jerry Stuckle wrote:
Sanders Kaufman wrote:

Wow, now that I've done it that way, I can see why it's the better way.
By having to call the parent constructor from within the child object, It gives the child better control.

For example, my parent has a "database" object, and a built-in default way of talking to it; while the child has another way of talking to it - each established in the constructor, and each running a verification process to ensure it still works


Probably an incorrect implementation of OO, depending on exactly what you're trying to do.

The purpose of OO is to allow the child object to use the parent object's methods (functions) and to not have to write its own.

In the case of a Database object, the main purpose of the object is to perform the communications. Another class which does it a different way would be a different class.


I probably used the phrase "different way" poorly.

What I mean is that my database class, by default, connects to my primary database server. But other classes in my architecture, extending that one, may need to contact a different server.

So, by having the child modify the parent connection parameters, it can talk to whoever it needs to... not just my primary.



Now that doesn't mean you shouldn't have a database object which doesn't have children. For instance, as a simple example, you might have:

class Database
member database name
abstract methods open (connect), close (disconnect), query

class MySQL_Database extends Database
methods open, close, query

class PostGres_Database extends Database
methods open, close query

But you should not have:

class MySQL_Database
member database name
methods open, close, query

class PostGres_Database extends MySQL_Database
methods open, close query (which override MySQL Database)

I know this isn't exactly what you're saying - but I wanted to make it more extreme to be more obvious.

It's ALL good - although every answer seems to beg another question!
In this case - abstract methods?
Is this another OOP thing that PHP4 doesn't do?


If you're basically creating a MySQL_Database class then overriding most of the methods in the child class, you should look at whether your design is appropriate or not.

Word.
Fortunately, I didn't fall into that trap.
In fact, in designing my project, I (wrongly) presumed that I could not overrride functions in PHP.


That's not to say overriding is *never* appropriate - in many cases it is. But as part of the overriding, you generally end up calling the parent class method, also.

?!
So if the parent has "$parent->foo",
And the child overrides that with "$child->foo",
BOTH functions will fire when the child does?!
... but only sometimes?

Wassat about?!

.

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