supersession

[matt_falcon]

In need to produce a component where by a data set supercedes another, and that the user always sees the superceded value.

 

For example:

 

X --> Y --> Z

 

As X is superceded by Y and then Z supercedes Y then the need to just view the latest value is onle needed, example:

 

X --> Z

 

Please can anyone help?

[genericnumber1]

I don't really understand. When it comes to data stored in variables, the newly added data has always superseded the old data... can you explain more thoroughly?

[matt_falcon]

Basically we have a number of different models which usually over time get replaced byanother model, meaninf it can be super ceded several times! So the result should be that the latest model should be shown, not the first model in the supersession series, e.g. model A gets super ceded by B, then by C. Therefore model A should show model C as the supersession model, not B.

 

Please can you can

[448191]

Your question is a bit vague, but maybe this is what you are looking for?

<?php
/**
* Chain of Responsibilty
*
*/
class DataChain
{
/**
 * Internal data
 *
 * @var array
 */
private $_data = array();

/**
 * Successor DataChain
 *
 * @var DataChain
 */
private $_successor;

/**
 * Set the successor
 *
 * @param DataChain $successor
 */
public function setSuccessor(DataChain $successor)
{
	$this->_successor = $successor;
}

/**
 * Get data by key
 *
 * @param string|int $key
 */
public function get($key)
{
	if(isset($this->_data[$key]))
	{
		return $this->_data[$key];
	}
	if($this->_successor !== null)
	{
		return $this->_successor->get($key);
	}
	return null;
}

/**
 * Set data by key
 *
 * @param string|int $key
 * @param mixed $value
 */
public function set($key, $value)
{
	return $this->_data[$key] = $value;
}
}
?>

 

Edit: Probably you want this:

 

/**
 * Get data by key
 *
 * @param string|int $key
 */
public function get($key)
{
	if($this->_successor !== null)
	{
		return $this->_successor->get($key);
	}
	if(isset($this->_data[$key]))
	{
		return $this->_data[$key];
	}
	return null;
}

 

It's no longer a Chain of Responsibility (rather the reverse), but if I understand correctly, this is what you are after.

[matt_falcon]

Thanks for the code! This is exactly what I was looking for  . Your help has been greatly appreciated Kind Regards

[448191]

You're welcome, though I don't really see in what situation you would want this. I'm pretty sure there is a better solution to the underlying problem...

[matt_falcon]

Well the situation is that we want our users to have access to the latest model of our product, not only do we want users to be able to view old models but a link to the latest model that super cedes that old model. Hopefully that gives you a better reason to why! Again thanks for you time.