app.Flags = []cli.Flag {
cli.StringFlag{
Name: "operation, o",
Value: "add",
Usage: "calc operation",
},
cli.Float64Flag{
Name: "numberone, n1",
Value: 0,
Usage: "number one for operation",
},
cli.Float64Flag{
Name: "numbertwo, n2",
Value: 0,
Usage: "number two for operation",
},
}
能看出，我们使用了三个参数：operation、numberone、numbertwo
同时定义了参数的类型，默认值，以及别名（缩写）
那么在这个框架中如何实现参数的操作呢：主要是重写app.Action 方法
app.Action = func(c *cli.Context) error {
operation := c.String("operation")
numberone := c.Float64("numberone")
numbertwo := c.Float64("numbertwo")
//fmt.Println(operation, numberone, numbertwo)
if operation == "add" {
rt := numberone + numbertwo
fmt.Println("Result ", rt)
} else if operation == "sub" {
rt := numberone - numbertwo
fmt.Println("Result ", rt)
} else if operation == "mul" {
rt := numberone * numbertwo
fmt.Println("Result ", rt)
} else if operation == "sqrt" {
rt := math.Sqrt(numberone)
fmt.Println("Result ", rt)
} else {
help()
}
return nil
}
# 对 operation 参数进行判断，执行的是那种运算，然后编写相应的运算操作
func CalcByCli(){
app := cli.NewApp()
app.Name = "calc with go"
app.Usage = "calc tool operate by go"
app.Version = "0.1.0"
app.Flags = [] cli.Flag {
cli.StringFlag{
Name: "operation, o",
Value: "add",
Usage: "calc operation",
},
cli.Float64Flag{
Name: "numberone, n1",
Value: 0,
Usage: "number one for operation",
},
cli.Float64Flag{
Name: "numbertwo, n2",
Value: 0,
Usage: "number two for operation",
},
}
app.Action = func(c *cli.Context) error {
operation := c.String("operation")
numberone := c.Float64("numberone")
numbertwo := c.Float64("numbertwo")
//fmt.Println(operation, numberone, numbertwo)
if operation == "add" {
rt := numberone + numbertwo
fmt.Println("Result ", rt)
} else if operation == "sub" {
rt := numberone - numbertwo
fmt.Println("Result ", rt)
} else if operation == "mul" {
rt := numberone * numbertwo
fmt.Println("Result ", rt)
} else if operation == "sqrt" {
rt := math.Sqrt(numberone)
fmt.Println("Result ", rt)
} else {
help()
}
return nil
}
app.Run(os.Args)
}
调用这个函数的最终效果如下：
./calc -o add --n1 12 --n2 12
Result 24
===================================
./calc -o sub --n1 100 --n2 200
Result -100
===================================
./calc -o mul --n1 10 --n2 20
Result 200
===================================
./calc -o sqrt --n1 2
Result 1.4142135623730951
4 其他
知道如何读取命令行参数，就可以实现一些更有意思的事。
比如网上有许多免费的 API 接口，比如查询天气，查询农历的API 接口。
还有一些查询接口，比如有道云翻译接口，你可以实现翻译的功能。
