Chaining

chaining/Makefile

@@ -0,0 +1,2 @@
+run:
+	@go run main.go

chaining/go.mod

@@ -0,0 +1,3 @@
+module patterns
+
+go 1.21.5

chaining/main.go

@@ -0,0 +1,53 @@
+package main
+
+import "fmt"
+
+type Filter struct {
+	alive      *bool
+	id         *int
+	externalId *string
+}
+
+func NewFilter() *Filter {
+	return &Filter{}
+}
+
+func (f *Filter) Dump() {
+	fmt.Println("Filter non-nil options:")
+	if f.alive != nil {
+		fmt.Printf("  Alive: %v\n", *f.alive)
+	}
+	if f.id != nil {
+		fmt.Printf("  Id: %v\n", *f.id)
+	}
+	if f.externalId != nil {
+		fmt.Printf("  ExternalId: %v\n", *f.externalId)
+	}
+}
+
+func (f *Filter) Alive(alive bool) *Filter {
+	f.alive = &alive
+	return f
+}
+
+func (f *Filter) Id(id int) *Filter {
+	f.id = &id
+	return f
+}
+
+func (f *Filter) ExternalId(externalId string) *Filter {
+	f.externalId = &externalId
+	return f
+}
+
+func main() {
+	var f *Filter
+
+	f = NewFilter().ExternalId("some-external-id")
+	f.Dump()
+
+	fmt.Println("-------------------")
+
+	f = NewFilter().Id(123).Alive(true).ExternalId("some-external-id")
+	f.Dump()
+}

config_pattern/main.go

@@ -54,7 +54,7 @@ func NewFilter(opts ...SetFilterFunc) *Filter {
 func main() {
 	var f *Filter
 
-	f = NewFilter()
+	f = NewFilter(WithExternalId("some-external-id"))
 	f.Dump()
 
 	fmt.Println("-------------------")