You'd have to clearly define what "calling the plugins" exactly mean.
For start, you can check out here how to require
all the files from a directory, put your plugins into a single directory and require them all.
Then you need to somehow pick which one to use, whether it be:
- passing its classname as a string through a command line argument or a config file parameter, and looking for a class by that name using
const_get
, or
- presenting a user a list of all plugins (all descendants of your
Plugin
class) - check out here how to do it
Finally, you instantiate your plugin and do whatever you need to do with it.