refactor!: make Option an interface

Signed-off-by: Mark Sagi-Kazar <[email protected]>

health.go

@@ -37,7 +37,7 @@ func New(opts ...Option) Health {
 		lock:       sync.RWMutex{},
 	}
 	for _, opt := range append(opts, WithDefaults()) {
-		opt(h)
+		opt.apply(h)
 	}
 	return h
 }

options.go

@@ -1,23 +1,37 @@
 package gosundheit
 
-type Option func(*health)
+// Option configures a health checker using the functional options paradigm
+// popularized by Rob Pike and Dave Cheney.
+// If you're unfamiliar with this style, see:
+// - https://commandcenter.blogspot.com/2014/01/self-referential-functions-and-design.html
+// - https://dave.cheney.net/2014/10/17/functional-options-for-friendly-apis.
+// - https://sagikazarmark.hu/blog/functional-options-on-steroids/
+type Option interface {
+	apply(*health)
+}
+
+type optionFunc func(*health)
+
+func (fn optionFunc) apply(h *health) {
+	fn(h)
+}
 
 // WithCheckListeners allows you to listen to check start/end events
 func WithCheckListeners(listener ...CheckListener) Option {
-	return func(h *health) {
+	return optionFunc(func(h *health) {
 		h.checksListener = listener
-	}
+	})
 }
 
 // WithHealthListeners allows you to listen to overall results change
 func WithHealthListeners(listener ...HealthListener) Option {
-	return func(h *health) {
+	return optionFunc(func(h *health) {
 		h.healthListener = listener
-	}
+	})
 }
 
 // WithDefaults sets all the Health object settings. It's not required to use this as no options is always default
 // This is a simple placeholder for any future defaults
 func WithDefaults() Option {
-	return func(h *health) {}
+	return optionFunc(func(h *health) {})
 }