Method Observer

extension/platform/builder.go:85–97

Observer registers an Observer. Multiple calls accumulate.

(when When, hookName string, sel Selector, fn Observer)

// Observer registers an Observer. Multiple calls accumulate.
func (b *Builder) Observer(when When, hookName string, sel Selector, fn Observer) *Builder {
	if !b.validateHookName(hookName, "observer") {
		return b
	}
	// Capture by value so the action closure doesn't share state with
	// subsequent Observer() calls (Go ≥1.22 already gives each call
	// its own copies of parameter values, but pinning is explicit).
	w, n, s, f := when, hookName, sel, fn
	b.actions = append(b.actions, func(r Registrar) {
		r.Observe(w, n, s, f)
	})
	return b
}

// Wrap registers a Wrapper. Multiple calls accumulate; the host
// composes them in registration order (outermost first).