PHP objects as faux-arrays

Question

I have an object that implements ArrayAccess, Iterator and Countable. That produces a nigh-perfect array masking. I can access it with offsets ($object[foo]), I can throw it into a foreach-loop, and many other things.

But what I can't do is give it to the native array iterator functions (next(), reset(), current(), key()), even though I have implemented the required methods from Iterator. PHP seems to stubbornly try to iterate through its member variables, and entirely disregards the iterator-methods.

Is there an interface that would hook the object to the remaining array-traversing-functions, or am I stuck with what I have?

Update: IteratorAggregate doesn't seem to be the answer either. While it is used in foreach-loops, the basic array iterator functions don't call the methods.

ringmaster · Accepted Answer · 2008-11-24 21:55:49Z

5

Recent changes in PHP prevent ArrayIterators form being manipulated using the standard array functions (reset, next, etc).

This should be restored soon: http://news.php.net/php.internals/42015

answered Nov 24, 2008 at 21:55

ringmaster

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Comments

majelbstoat · Accepted Answer · 2008-11-24 21:44:52Z

3

One way to get this to work is to define your own iterator in a separate class, and then tell your main class to use that new iterator instead of the default one.

class MyIterator implements Iterator {
  public function key() {
    //
  }

  public function rewind() {
    //
  }

  // etc.

}

class MyMainClass implements IteratorAggregate {
  private $_data = array();

  // getIterator is required for the IteratorAggregate interface.
  public function getIterator() {
    return new MyIterator($this->_data);
  }

  // etc.

}

Then you should have as much control as you need. (And you can reuse your own MyIterator across a number of classes).

No testing done on the above, but the principle is correct, I believe.

Hope this helps!

edited Nov 24, 2008 at 21:44

answered Nov 24, 2008 at 21:36

majelbstoat

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3 Comments

Henrik Paul Over a year ago

For some strange reason, this doesn't work for me. It's as if the custom iterator never gets called with the basic array iterator functions.

Peter Bailey Over a year ago

The ArrayObject implementation already has a get/set convention for the Iterator

majelbstoat Over a year ago

Sure, but ArrayObject is a concrete class, not an interface, so you have to extend it, not implement it. And, given that you can only extend from one class, I'd choose to do it this way. Better separation of concerns too, I think. YMMV :)

Peter Bailey · Accepted Answer · 2008-11-24 21:25:44Z

0

Is ArrayIterator not what you're looking for? Or what about ArrayObject, which seems to be SPL's interface for what you're trying to achieve.

answered Nov 24, 2008 at 21:25

Peter Bailey

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1 Comment

Henrik Paul Over a year ago

Actually, those are not interfaces, but implementations. But, now that you mention it, ArrayObject does seem to react as expected to function calls such as reset($arrayObject);

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