From e09f4dc6b872e29cf232511b009e69f0592e9350 Mon Sep 17 00:00:00 2001
From: Arseny Balobanov <verytable@yandex.ru>
Date: Thu, 25 Feb 2021 14:42:06 +0300
Subject: [PATCH] [lectures/02-interfaces] Add errors.As example.

---
 lectures/02-interfaces/lecture.slide     |  4 ++++
 lectures/02-interfaces/temporary/main.go | 18 ++++++++++++++++++
 2 files changed, 22 insertions(+)
 create mode 100644 lectures/02-interfaces/temporary/main.go

diff --git a/lectures/02-interfaces/lecture.slide b/lectures/02-interfaces/lecture.slide
index 5dae78b..a2006cd 100644
--- a/lectures/02-interfaces/lecture.slide
+++ b/lectures/02-interfaces/lecture.slide
@@ -475,3 +475,7 @@ As
   if perr, ok := err.(*os.PathError); ok {
       fmt.Println(perr.Path)
   }
+
+* errors.As
+
+.play temporary/main.go
diff --git a/lectures/02-interfaces/temporary/main.go b/lectures/02-interfaces/temporary/main.go
new file mode 100644
index 0000000..056b0f8
--- /dev/null
+++ b/lectures/02-interfaces/temporary/main.go
@@ -0,0 +1,18 @@
+package main
+
+import "errors"
+
+type Temporary interface {
+	IsTemporary() bool
+}
+
+func do() error { return nil }
+
+func main() {
+	err := do()
+
+	var terr Temporary
+	if errors.As(err, &terr) && terr.IsTemporary() {
+		//...
+	}
+}