代码实现

下面是一个简单的画画的例子，默认的 Line  只有基础的画画功能， ColorLine  为他加上了颜色，本质上是对现有功能类进行包装，增加新功能点

Code

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package decorator  
  
// IDraw IDraw  
type IDraw interface {  
   Draw() string  
}  
  
// Line 划线  
type Line struct{}  
  
// Draw Draw  
func (l Line) Draw() string {  
   return "Drawing a line here"  
}  
  
// ColorLine 有颜色的线  
type ColorLine struct {  
   line IDraw  
   color  string  
}  
  
// NewColorLine NewColorLine  
func NewColorLine(line IDraw, color string) ColorLine {  
   return ColorLine{color: color, line: line}  
}  
  
// Draw Draw  
func (c ColorLine) Draw() string {  
   return c.line.Draw() + ", color is " + c.color  
}

单元测试

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func TestColorLine_Draw(t *testing.T) {  
   l := Line{}  
   ncl := NewColorLine(sq, "red")  
   got := ncl.Draw()  
   assert.Equal(t, "Drawing a line here, color is red", got)  
}