feedkit: split the former maximumdirect.net/weatherd project in two.

feedkit now contains a reusable core, while weatherfeeder is a concrete implementation that includes weather-specific functions.

sinks/registry.go

@@ -0,0 +1,33 @@
+package sinks
+
+import (
+	"fmt"
+
+	"gitea.maximumdirect.net/ejr/feedkit/config"
+)
+
+// Factory constructs a sink instance from config.
+//
+// This is the mechanism that lets concrete daemons wire in whatever sinks they
+// want without main.go being full of switch statements.
+type Factory func(cfg config.SinkConfig) (Sink, error)
+
+type Registry struct {
+	byDriver map[string]Factory
+}
+
+func NewRegistry() *Registry {
+	return &Registry{byDriver: map[string]Factory{}}
+}
+
+func (r *Registry) Register(driver string, f Factory) {
+	r.byDriver[driver] = f
+}
+
+func (r *Registry) Build(cfg config.SinkConfig) (Sink, error) {
+	f, ok := r.byDriver[cfg.Driver]
+	if !ok {
+		return nil, fmt.Errorf("unknown sink driver: %q", cfg.Driver)
+	}
+	return f(cfg)
+}