根据map [string] somestruct调用golang调度方法 [英] golang dispatch method call according to a map[string]somestruct

问题描述

假设我有很多带有接收器的函数或方法，每个函数或方法都有不同类型的参数.我想使用表驱动的方法来调度函数或方法调用.因此，我将构建一个像这样的表:

Assuming I have lots of functions or methods with receiver, each of which has different type of parameters. I want to use table-driven method to dispatch function or method call. So I'll construct a table like this:

type command struct {
   name string
   handler func(parameter ...interface{}) // I don't know whether to use `...interface{}` is correct
}

table := map[string]command { ... }

func (c command)foo(f1 int, f2 string) {}
func (c command)bar(b1 bool, b2 int, b3 string) {}
// methods and so on

无论我收到什么命令，我将始终使用诸如 table [some-command-name](parameter1，parameter2，...)之类的一条语句，而不要使用难看的switch-case结构.

No matter what command I receive, I'll always use one statement like table[some-command-name](parameter1, parameter2, ...) instead of using the ugly switch-case structure.

这可能吗?难道不同的方法有不同数量的参数是一个问题吗?

Is this possible ? That different methods have different number of parameters is a problem ?

推荐答案

有两种可能的方法.一种是通过反射，即 reflect 包，尤其是 Call 方法.第二个是通过函数值和闭包.我不推荐第一种解决方案，通常不建议使用反射，因为它很复杂，容易出错并且价格昂贵.

There are two possible ways. One is through reflection, that is reflect package and in particular the Call method. The second one is through function values and closures. I would not recommend the first solution, reflection is generally discouraged because it is complicated, error prone and expensive.

反思解决方案( https://play.golang.org/p/3b5I77QMsFI ):

type command struct {
    name    string
    handler reflect.Value
    args    []reflect.Value
}

var table = map[string]command{
    "Foo": {
        name:    "Foo",
        handler: reflect.ValueOf(foo),
        args: []reflect.Value{
            reflect.ValueOf(1),
            reflect.ValueOf("hello"),
        },
    },
    "Bar": {
        name:    "Bar",
        handler: reflect.ValueOf(bar),
        args: []reflect.Value{
            reflect.ValueOf(true),
            reflect.ValueOf(5),
            reflect.ValueOf("hello"),
        },
    },
}

func foo(f1 int, f2 string) {
    fmt.Println("Foo:", f1, f2)
}
func bar(b1 bool, b2 int, b3 string) {
    fmt.Println("Bar:", b1, b2, b3)
}

func main() {
    for name, command := range table {
        fmt.Println("Running", name)
        command.handler.Call(command.args)
    }
}

通过函数闭包( https://play.golang.org/p/8fM86lxalq1):

type MyFuncType func()

type command struct {
    name    string
    handler MyFuncType
}

var table = map[string]command{
    "Foo": {
        name:    "Foo",
        handler: fooClosure(1, "hello"),
    },
    "Bar": {
        name:    "Bar",
        handler: barClosure(true, 5, "hello"),
    },
}

func foo(f1 int, f2 string) {
    fmt.Println("Foo:", f1, f2)
}

func fooClosure(f1 int, f2 string) MyFuncType {
    return func() {
        foo(f1, f2)
    }
}

func bar(b1 bool, b2 int, b3 string) {
    fmt.Println("Bar:", b1, b2, b3)
}

func barClosure(b1 bool, b2 int, b3 string) MyFuncType {
    return func() {
        bar(b1, b2, b3)
    }
}

func main() {
    for name, command := range table {
        fmt.Println("Running", name)
        command.handler()
    }
}

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