Merge pull request #51 from tsingbx/method-values

Add doc for method values and expressions

213-Method-Values-and-Expressions/method-values-1.gop

@@ -0,0 +1,19 @@
+
+# Method value
+
+// Method values allow you to bind a method to a specific object, and then call the method as an ordinary function with the object implied, in a kind of closure. For example:
+
+type Hello struct {
+}
+
+func (hello *Hello) Say() {
+	println "Hello"
+}
+
+hello := &Hello{}
+
+hello.Say
+
+printf("%T", hello.Say)
+
+// The expression hello.Say creates a method value, binding the Say function to the specific variable hello, giving it a type of func(). So function values can be passed as function parameters

213-Method-Values-and-Expressions/method-values-2.gop

@@ -0,0 +1,25 @@
+
+# Method expressions
+
+// Method expressions let you transform a method into a function with the receiver as its first argument. For example:
+
+type Point struct {
+	x float64
+	y float64
+}
+
+func (p Point) Add(another Point) Point {
+	return Point{p.x+another.x, p.y+another.y}
+}
+
+func (p Point) String() string {
+	return sprintf("x: %.1f, y: %.1f", p.x, p.y)
+}
+
+p := Point{20, 10}
+another := Point{30, 40}
+
+println p.Add(another)
+println Point.Add(p, another)
+
+// So if you defined a Point struct and a method func (p Point) Add(another Point), you could write Point.Add to get a func(p Point, another Point).

213-Method-Values-and-Expressions/method-values-3.gop

@@ -0,0 +1,24 @@
+
+// But if the method has a pointer receiver, you need to write (*Type).Method in your method expression. For example:
+
+type Point struct {
+	x float64
+	y float64
+}
+
+func (p *Point)Add(another Point) {
+	p.x += another.x
+  p.y += another.y
+}
+
+func (p *Point) String() string {
+	return sprintf("x: %.1f, y: %.1f", p.x, p.y)
+}
+
+p := &Point{20, 10}
+another := Point{30, 40}
+
+p.Add(another)
+(*Point).Add(p, another)
+
+println p