hungry hippos OO problem

norpel

Hi all,

I've been designing some php classes based tightly around the tutorial here

basically...

class_base
hippos extend class_base)
armedhippos extend hippos)

my question is this.

if I wanted to store armed hippos in a separate table in my database, how/where would I define the table name for this.

I've tried it (this->table_name='armedhippo') in the constructor for the armed hippo class, but since it extends from the hippo it seems to get overwritten in the constructor for the hippo class.

surely I don't need to store all of them in one table,

am i missing something obvious?

(i've attached the source code for this example for those who don't want to wade through the tutorial)

thanks,
norpel

swr

I've tried it (this->table_name='armedhippo') in the constructor for the armed hippo class, but since it extends from the hippo it seems to get overwritten in the constructor for the hippo class.

That should work fine, as long as you do it after calling the parent's constructor (parent::Hippo()).

norpel

hi swr,

after alot of scratching my head I worked this out, but then I was faced with the problem that

$this->table_name=='armedhippo'

but my table for armedhippo only has the extra elements that aren't contained in table hippo

|hippos

| id

| name

----------------------------
| armedhippo

| id

| num_mount_points

I can write functions in class hippo which utilise (extend) the functions in class hippo, but when these are called, instead of being able to find name they return with an error because they are looking to $this->table_name (which is now armedhippo) for their data.

Is there a way around this. I'm sure there must be but apart from adding subtable variables into the hippo class just for the classes that it spawns, I can't think of how this can be done. (I'm pretty sure this is not the way to do this as it seems to defeat the point of OOP)

thanks for your help,
norpel

norpel

while browsing the oo methods in php 5 I came across this

Constants

Constants

PHP 5 introduces per-class constants:

<?php

class Foo
{ const constant = "constant"; }

echo "Foo::constant = " . Foo::constant . "\n";

?>

would this solve my problem, allowing me to keep hippo::table_name different from armedhippo:: table_name?

swr

I guess that would work. With PHP4, you could have a function, and call it by class instead of instance:
Hippo::table_name()
ArmedHippo::table_name()

norpel

just finished installing v5... so I'll probably go with the constants, maybe there will be some other useful additions too, it seems to be alot more OO orientated.

thanks for your help,
norpel