OOP Question -> Object to contain a collection of objects

[enoch]

Greetings,

 

The scenario:

class Book contains some simple information about a book such as title and width of book.

class BookShelf contains a collection of book objects which it can keep track of and also can monitor how many book objects it can fit based on their width.

 

Simple concept right? Well, I am having a bit of difficulty in creating the BookShelf class to contain and manage the book objects.

 

I believe the PHP SPL stuff may be the way to go on this but am not sure.

Any suggestions, links, or pointers would be greatly welcome!

 

Thanks,

Enoch

[enoch]

Just adding some information and curious what you folks know about this:

 

The SplObjectStorage class (part of the SPL) seems ideal for this. 

http://us2.php.net/manual/en/class.splobjectstorage.php

 

Does anyone have experience using it?

If so, would I create class BookShelf (from the scenario) and then create a new SplObjectStorage object within it?  something along these lines:

 

class BookShelf{

public $shelf;

function __construct{

  $this->shelf =new SplObjectStorage();

}

}

 

and then work with it from there?  is that even the proper way to implement it... testing to commence - advice encouraged and appreciated!

 

}

 

[enoch]

This is what I have so far... but it isn't working... yet.

 

<?php

// BOOK Class /////////////////////////

class Book{

  public $title = "";

  public $width = "0";

 

  function __construct($title, $width){

    $this->title = $title;

    $this->width = $width;

  }

 

}

///////////////////////////////////////

 

// BOOKSHELF Class /////////////////////////

class BookShelf{

public $shelf;

public $obj;

 

function __construct(){

  $this->shelf =new SplObjectStorage();

}

 

function addBook($obj){

  $this->obj = $obj;

  $this->shelf->attach($this->obj);

}

 

function removeBook($obj){

  $this->obj = $obj;

  $this->shelf->detach($this->obj);

}

 

function checkBook($obj){

  $this->obj = $obj;

  $this->shelf->contains($this->obj);

}

 

}

////////////////////////////////////////////

 

 

$b1 = new Book("Title1","2");

$b2 = new Book("Title2","2");

$b3 = new Book("Title3","2");

 

$bs = new BookShelf();

 

$bs->addBook($b1);

 

var_dump($bs->checkBook($b1));

echo "<br />";

 

$bs->removeBook($b1);

 

var_dump($bs->checkBook($b1));

echo "<br />";

 

?>

[Daniel0]

That would be okay, with a few exceptions:

 

1) Your properties shouldn't be public.

2) What is up with $this->obj = $obj; all over the place?

3) A width is a numeric value. Why are you storing it as a string? Use a float or int depending on your needs.

[ToonMariner]

not quite sure why you need the bookshelf class - perhaps the book object itself would benefit from having a shelfmark member and status (whether its in lib or not).

 

Just appears to me that would provide with a simpler solution...

[Daniel0]

not quite sure why you need the bookshelf class

 

Not if you're like me and your books are all over the place at least.

[ToonMariner]

[enoch]

Hi Daniel0 - thanks for taking a look at this stuff...

Couple things... the example I have here does not work- so it really is not ok.

 

1) ok, makes sense to have them private.

2) I am using the $obj as the variable to store the book object being worked on by the methods... am I missing something with this?

3) yep, no need for quotes on my numeric stuff ... g!

 

How familiar are you with the PHP SPL, in particular SplObjectStorage?  Why are these <tt>var_dump($bs->checkBook($b1));</tt>  returning nulls in the example code?

 

That would be okay, with a few exceptions:

 

1) Your properties shouldn't be public.

2) What is up with $this->obj = $obj; all over the place?

3) A width is a numeric value. Why are you storing it as a string? Use a float or int depending on your needs.

[Daniel0]

2) I am using the $obj as the variable to store the book object being worked on by the methods... am I missing something with this?

 

Well, you can just do like this:

function addBook($obj){
  $this->shelf->attach($obj);
}

 

How familiar are you with the PHP SPL, in particular SplObjectStorage?  Why are these <tt>var_dump($bs->checkBook($b1));</tt>  returning nulls in the example code?

 

Because your method isn't returning anything.