Registering Plugins With Decorators

00:01 In this last example, I’ll show you how you can register functions using a decorator, sort of like registering plugins. For this final example, I’m going to have you work just inside the REPL. Start by importing random.

00:16 You’ll see why in a moment and how you’re going to use it. Make a dictionary named PLUGINS. Make a decorator. Its name is register().

00:28 It’s going to look very different from the ones that you’ve made up to this point—a little simpler. It will have a docstring saying that it’s designed to """Register a function as a plug-in""".

00:39 Using PLUGINS, take that func that comes in—”Yeah, that funk that comes in”—and using the .__name__ method, add it to functions.

00:52 Then, return the function unchanged. Great. There’s register().

01:00 Now use that as a decorator as you define… These are functions that you created a long time ago. say_hello() takes a name as an argument and returns an f-string, with a very simple f"Hello ", and name as the expression.

01:19 There’s say_hello(). And register this one also. It’s called be_awesome(). It takes a name as an argument and this time returns an f-string with the expression name in it.

01:40 All right. What’s inside PLUGINS now? PLUGINS now has two functions inside of it as the dictionary: say_hello and be_awesome. Pretty cool! Well, how are you going to use it? Next, you’re going to make a function called randomly_greet().

01:59 It takes a name as an argument.

02:05 A greeter and a greeter function—here’s where we’re using random. With the method choice() it’s going to pull out of PLUGINS—we’ll make it into an iterator by using the method .items(). Close off all those parentheses.

02:21 So, random.choice() out of the PLUGINS dictionary to populate greeter and greeter_func. Using print(), make an f-string saying f"Using " which greeter in its repr() version. Close off the print statement. And then return with a call to that greeter() function, with the name that has been passed in. All right!

02:48 I’ll make some space. Now, randomly_greet() is available and let’s say you want to greet "Alice". So here, it’s saying that it’s using the greeter function 'be_awesome', so it randomly picked that one. Try it again. Now it used 'say_hello'.

03:07 Pretty neat! So you could have multiple functions that you’re registering in to create this simplified plugin architecture.

03:17 The main benefit of this simple architecture is that you don’t actually have to maintain a list of which plugins exist. The list gets created every time you register a plugin by applying the decorator to any of those functions, which is pretty neat! Okay.

03:33 It’s time to wrap up Decorators 101 with a final review.