$amount = 0x1FFFF;
$start = microtime(true);

while ($amount--)
	$throwAway = "this is a test at the $amount point!"; //$throwAway = "this is a test at the ". $amount ." point!";

	echo "Time: ". (microtime(true) - $start);

Exactly as expected, leaving it up to in-string parsing of variables ended up with a bench mark time of 0.1574 and manually concatenating in the variable was 0.1384, which is not a huge difference, but I wanted to see how this would scale when doing multiple concatenations. The string was changed to $throwAway = "this is ". $amount ." a test ". $amount ." at the ". $amount ." point!"; and it's respective in-string.

What I found is that it actually scales to in-string far better! In-string averaged to 0.3235 and manual to 0.3597. After some research it turns out this is because it does a single large concatenation while manually doing it could perform the operation 3 separate times.

Index Checking

The functional difference between array_key_exists($key, $array) and isset($array[$key]) is that isset returns false when the key exists but contains null. Functionality aside, there is a demonstrable performance difference.

$dataSet = array();
$size = 0x1FFFF;

$i = $size;
while ($i--)
	$dataSet[$i] = $i+1;

$start = microtime(true);

$i = $size;
while ($i--)
	array_key_exists($i, $dataSet); //isset($dataSet[$i]);

echo "Time: ". (microtime(true) - $start);

Sure enough, after averaging a few benchmarks together the outcome was clear.

isset

0.0248870849609

array_key_exists

0.604112148285

When performance is important target isset() when applicable. It's even possible to use a fall through to increase performance, here's an example from my Options class: if (!isset($this->_options[$resolvedName]) && !array_key_exists($resolvedName, $this->_options))

In the following test case there was no performance difference between usage of append or directly addressing an index.

$dataSet = array();
$size = 0x1FFFF;
$i = $size;

$start = microtime(true);

while ($i--)
	$dataSet[] = $i+1; //$dataSet[$i] = $i+1;

echo "Time: ". (microtime(true) - $start);

I have designed a pattern that allows an object to accept and address public level optional named arguments without the problems that could be associated with the compact()/extract() pattern. This pattern does require at least PHP 5.3 (uses late static binding) and overloads __get/__set preventing the child class from doing so.

Possible optional keys are defined as class constants, if one is addressed or set that is undefined an exception will be thrown. Instead of using extract(), the inherited SetOptionalProperties($array) method should be called to set the values. The value's can be addressed by it's constants name like it's a property, like $instance->ConstantName. Default values can be given by overloading the protected static $_defaultOptions member. The example shows this in with more detail:

class MyClass extends Options {
	public $Property;

	const MyOption = "MyOption";
	const AnotherOption = "AnotherOption";

	protected static $_defaultOptions = array(self::AnotherOption = "default value!");

	public function __construct($property, $options = array()) {
		$this->Property = $property;
		$this->SetOptionalProperties($options); // this allows Options to access the optional values.
	}
}

$instance = new MyClass("property's value", array(MyClass::MyOption = "my option value!"));
echo "MyOption: '{$instance->MyOption}', AnotherOption: '{$instance->AnotherOption}', Property: '{$instance->Property}'";

MyOption: 'my option value!', AnotherOption: 'default value!', Property: 'property's value'

abstract class Options {
	/// The array which stores the optional values
	private $_options = array();

	/// This array should be overloaded by child classes if default values are going to be used.
	protected static $_defaultOptions = array();

	/// Use Options::$AllowUndefinedProperties = true; to prevent exceptions from being thrown when an undefined
	/// property is set or fetched.
	public static $AllowUndefinedProperties = false;

	public function &__get($name) {
		$resolvedName = $this->ResolveOptionName($name);

		// Do we have a value? Use the isset/array_key_exists fall through to speed up access to existing non-null entries.
		if (!isset($this->_options[$resolvedName]) && !array_key_exists($resolvedName, $this->_options)) {
			// Do we have a default value?
			if (array_key_exists($resolvedName, static::$_defaultOptions))
				$this->_options[$resolvedName] = static::$_defaultOptions[$resolvedName];
			else
				$this->_options[$resolvedName] = null;
		}

		return $this->_options[$resolvedName];
	}

	public function __set($name, $value) {
		$resolvedName = $this->ResolveOptionName($name);

		return $this->_options[$resolvedName] = $value;
	}

	public function __isset($name) {
		$resolvedName = $this->ResolveOptionName($name);

		return isset($this->_options[$resolvedName]);
	}

	public function __unset($name) {
		$resolvedName = $this->ResolveOptionName($name);

		unset($this->_options[$resolvedName]);
	}

	/**
	 * Set the optional properties for the class.
	 * @param $options A [ClassConstant] = Value indexed array of optional properties.
	 */
	protected function SetOptionalProperties(array $options) {
		$this->_options = $options;
	}

	/// Resolve any aliases name to the proper name.
	private function ResolveOptionName($name) {
		$constant = "static::". $name;

		if (defined($constant))
			return constant($constant);
		else if (!self::$AllowUndefinedProperties)
			throw new Exception("Undefined property or option '$name' being set in ". get_called_class());

	}
}

SELECT Foods.Description, concat( NutrientValue, Units ) AS Value
FROM Foods
JOIN NutrientDefinitions ON ( NutrientName = 'Protein' )
JOIN NutrientData
USING ( NutrientID, FoodID )
ORDER BY NutrientValue DESC
LIMIT 150

SELECT Foods.Description, concat( NutrientValue, Units ) AS Value
FROM FoodGroups
JOIN Foods
USING ( CategoryID )
JOIN NutrientDefinitions ON ( NutrientName = 'Protein' )
JOIN NutrientData
USING ( NutrientID, FoodID )
WHERE FoodGroups.Description like '%LEGUME%'
ORDER BY NutrientValue DESC
LIMIT 100

SELECT Foods.Description, concat( NutrientValue, Units ) AS Value
FROM Foods
JOIN NutrientDefinitions ON ( NutrientName like '%Iron%' )
JOIN NutrientData
USING ( NutrientID, FoodID )
ORDER BY NutrientValue DESC
LIMIT 150

I thought an interesting implementation would be a completely client side one written in Javascript using Google's search API. To spoil the ending, after creating this I discovered the API only allows 8 results per page and 8 pages, making this useless if the site is beyond the 64th result, but the API is interesting and powerful regardless.

The finished version can be found at pagerank.red-stars.net with the complete Javascript.

The WebSearch() object is relatively simple, once instanced, all it needs is a call back to be setup before it can be used.

var webSearch = new google.search.WebSearch();
webSearch.setSearchCompleteCallback(this, searchComplete, null);
webSearch.execute("cookies");

The function searchComplete() will be called when the search for "cookies" completes. It's important that our instance of WebSearch named webSearch is inside of a scope which is viewable from searchComplete() because the callback is argumentless.

function searchComplete() {
	// Make sure that there are results.
	if (webSearch.results && webSearch.results.length > 0) {
		var results = webSearch.results;
		// Go through every result.
		for (var resultIndex = 0; resultIndex < results.length; resultIndex++) {
			var result = results[resultIndex];
			// Show a messagebox with the results information.
			alert(result.html.innerHTML);
		}
	}
}

We used the .html property from the result which gives us a Google-looking result. Now what if we wanted more than just the first page?

var currentPageIndex = 0;
function searchComplete() {
	// Make sure that there are results.
	if (webSearch.results && webSearch.results.length > 0) {
		currentPageIndex++;
		var results = webSearch.results;
		// Go through every result.
		for (var resultIndex = 0; resultIndex < results.length; resultIndex++) {
			var result = results[resultIndex];
			// Show a messagebox with the results information.
			alert(result.html.innerHTML);
		}

		// Check if another page exists, if so, perform the request.
		if (currentPageIndex < webSearch.cursor.pages.length)
			webSearch.gotoPage(currentPageIndex);
	}
}

The cursor object contains an array called pages who's length is used to determine the number of pages available. This will go through all available search results. When gotoPage is called, our call back function is once again executed when the search is finished.

A complete reference to the WebSearch and associate classes is available on code.google.com. The API is decent and flexible, if not limited in functionality.