adding docs and examples of time.NewTimer

Author: symonk

README.md

@@ -23,3 +23,4 @@ all the examples `Run` functions sequentially in line with the table of contents
 * [09 - Slices](slices/main.go)
 * [10 - Maps](maps/main.go)
 * [11 - Range](ranges/main.go)
+* [12 - Timers](timers/main.go)

main.go

@@ -14,6 +14,7 @@ import (
 	"github.com/symonk/learning-golang/ranges"
 	"github.com/symonk/learning-golang/slices"
 	"github.com/symonk/learning-golang/switches"
+	"github.com/symonk/learning-golang/timers"
 	"github.com/symonk/learning-golang/values"
 	"github.com/symonk/learning-golang/variables"
 )
@@ -31,6 +32,7 @@ var (
 		slices.Run,
 		maps.Run,
 		ranges.Run,
+		timers.Run,
 	}
 )
 

timers/main.go

@@ -0,0 +1,46 @@
+package timers
+
+import (
+	"fmt"
+	"time"
+)
+
+/*
+Timers are a great mechanism for achieving:
+  - Running code at set intervals.
+  - Running code at some point in the future.
+
+`Tickers` are very similar to `Timers` so take a look at those aswell.
+*/
+func Run() {
+	basicTimer()
+	cancellingATimer()
+}
+
+func basicTimer() {
+	/*
+		Timers represent a single event in the future.  They are underpinned by
+		an unbuffered channel.  Creating a new timer takes a duration after which
+		it will fire.  The channel on a timer is set on the `C` attribute.
+	*/
+	timer := time.NewTimer(2 * time.Second)
+	fmt.Println("Timer started... we are blocking waiting for 2 seconds.")
+	<-timer.C // wait for the timer channel to be unblocked
+	fmt.Println("Timer fired after a 2 second delay")
+	timer.Reset(2 * time.Second)
+	fmt.Println("Reset the timer to use again!")
+	<-timer.C
+}
+
+func cancellingATimer() {
+	// Timers can be cancelled before they fire
+	t := time.NewTimer(60 * time.Second)
+	// Launch an async goroutine to wait on the timer and fire a task
+	go func() {
+		<-t.C
+		fmt.Println("The timer finished!")
+	}()
+	t.Stop()
+	fmt.Println("The timer was cancelled")
+
+}