Php extends from a different runtime class (expands as a variable?)

Question

It will be weird. I have a database class for MySQL and independent classes. For instance:

class users extends MySQL 

this class is a common class for users, so it can be used more than once. But sometimes the class "MySQL_DEBUGGED" is present, and if so, I want to switch from it:

 class users extends MySQL_DEBUGGED 

I want to inherit MySQL_DEBUGGED if present, otherwise the MySQL class. If I put it in a variable, this will result in an error. How to do it?

Answer 1

I do not think that you can inherit from a class whose name is not written in a PHP script.

Possible Solution:

• to define two classes called MySQL in two separate files
• so that your users class always extends the MySQL class (which means one of these two)
• Depending on the situation:
  • a file containing the MySQL "production" class,
  • or file containing the MySQL class

Thus, your class always extends the MySQL class, but you enable it.

Basically, in your main file, you would:

 if (DEBUG) { require __DIR__ . '/MySQL-debug.php'; } else { require __DIR__ . '/MySQL-production.php'; } class users extends MySQL { // ... } 

And both MySQL-debug.php and MySQL-production.php will contain a class called MySQL , which, of course, will not contain the same material in both files.

Answer 2

All you have to do is use the class_exists() function.

 if (class_exists('MySQL_DEBUGGED')) { class users extends MySQL_DEBUGGED { .... } } else { class users extends MySQL { .... } } 

I would not recommend it. Conditionally declaring classes seem like a nightmare.

Answer 3

The simplest solution is to have an empty "bridge" class and always inherit from it.

Then the only class you would need to declare twice will be empty.

 if (class_exists('MySQL_DEBUGGED')) { class MySQLBridge extends MySQL { } } else { class MySQLBridge extends MySQL_DEBUGGED { } } class User extends MySQLBridge { // ... your code ... } 

And finally, on your pages:

 require_once('User.php'); $user = new User(); 

Other proposed solutions require two copies of your inherited class, which I do not recommend.