PHP Constant Arrays: Is It Possible?

[John Creighto]

I was wondering if was possible to create a constant array in php so it doesn't have to be reinitialized each time you enter a function. I guess one solution is to make it global but from a code maintenance perspective it makes since to put the array in with the function that uses it.

 

[CompuChip]

If I understand your question correctly, you might be looking for a static variable.
I used it myself in the following two constructions (incidentally, from the same file, so I'll post them both):

	function connect_db() {	
		static $theDatabase = null;
		if(!$theDatabase) {
			global $databaseProperties;
			include("database.php");
			$theDatabase = new db($databaseProperties['dbname'], $databaseProperties['host'], $databaseProperties['user'], $databaseProperties['password'], $databaseProperties['persist']);
		}
		return $theDatabase;
	}

	function getLanguageList() {
		static $languageList = null;
		global $db;
		if($languageList === null) {
			if(!$db) $db = connect_db();
			$languageList = $db->q("column SHOW COLUMNS FROM `TranslatedStrings`");
		}
		return $languageList;
	}

In both functions, the static variable only exists within the function, but not outside it. The value is kept between calls however. For example, I can call connect_db() as much as I like. The first time, it will create a new database handle, store it in the static variable and give it to me. However, every next time I call the function, it will see that the variable has already been assigned and will just return the value.

The second example is more similar to your question, that's why I included it. The first time, an array is initialized with some values from a database, a relatively slow operation. After that however, the function basically does nothing but "return $languageList;" where $languageList has the value from the first call.

 

[quicknote]

Yes, it is possible to create a constant array in PHP. Constants in PHP are defined using the "define()" function, and arrays can be defined as constants by passing them as the second parameter in the function. This allows the array to be accessed and used within any function without needing to be reinitialized each time.

However, as you mentioned, using global variables can also achieve the same result. It ultimately depends on the specific use case and coding style preferences. Some developers may prefer to keep all constants in one file for easier maintenance, while others may prefer to keep them within the function that uses them.

In general, it is recommended to use constants for values that do not change throughout the execution of the script, such as configuration settings or fixed values. This can help improve code readability and maintainability.