From 59865eac283b416a911d2aa9ca00e16d5e7da226 Mon Sep 17 00:00:00 2001
From: Inanc Gumus <m@inanc.io>
Date: Mon, 21 Oct 2019 12:47:04 +0300
Subject: [PATCH] add: summaries iface

---
 interfaces/09-little-refactor/main.go | 15 +++++++++++++++
 interfaces/10-stringer/main.go        | 14 ++++++++++++++
 2 files changed, 29 insertions(+)

diff --git a/interfaces/09-little-refactor/main.go b/interfaces/09-little-refactor/main.go
index 5561cf3..726fe8d 100644
--- a/interfaces/09-little-refactor/main.go
+++ b/interfaces/09-little-refactor/main.go
@@ -17,3 +17,18 @@ func main() {
 	l.discount(.5)
 	l.print()
 }
+
+/*
+Summary:
+
+- Prefer to work directly with concrete types
+  - Leads to a simple and easy to understand code
+  - Abstractions (interfaces) can unnecessarily complicate your code
+
+- Separating responsibilities is critical
+  - Timestamp type can represent, store, and print a UNIX timestamp
+
+- When a type anonymously embeds a type, it can use the methods of the embedded type as its own.
+ - Timestamp embeds a time.Time
+ - So you can call the methods of the time.Time through a timestamp value
+*/
diff --git a/interfaces/10-stringer/main.go b/interfaces/10-stringer/main.go
index be85bef..7e114a6 100644
--- a/interfaces/10-stringer/main.go
+++ b/interfaces/10-stringer/main.go
@@ -32,3 +32,17 @@ func main() {
 	// var pocket money = 10
 	// fmt.Println("I have", pocket)
 }
+
+/*
+Summary:
+
+- fmt.Stringer has one method: String()
+  - That returns a string.
+  - It is better to be an fmt.Stringer instead of printing directly.
+
+- Implement the String() on a type and the type can represent itself as a string.
+  - Bonus: The functions in the fmt package can print your type.
+  - They use type assertion to detect if a type implements a String() method.
+
+- strings.Builder can efficiently combine multiple string values.
+*/