如何正确使用.调用反射包 [英] How to properly use .Call in reflect package

问题描述

我的代码遇到了最后一个问题，该问题涉及反射包中的.Call函数.

Been having one last issue with my code which involves the .Call function in the reflect package.

所以我正在打这样的电话:

So I'm making a call such as this:

params := "some map[string][]string"
in := make([]reflect.Value,0)
return_values := reflect.ValueOf(&controller_ref).MethodByName(action_name).Call(in)

我调用.call的方法如下:

where the method I'm making the .Call to is as follows:

func (c *Controller) Root(params map[string][]string) map[string] string{}

我不太了解的是如何操作"in"变量，以便将所需的映射正确传递到函数中.我看到make()中的第二个参数是参数的长度吗?但是我不太了解如何格式化var以便正确传递我的参数.我递归地遇到错误消息:

What I don't quite understand is how to manipulate the "in" variable in order to properly pass the map I need to into the function. I see that the second parameter in the make() is the length of the parameter? But I don't quite understand how to format the vars in order to properly pass in my parameter. I am recursively running into the error message:

reflect: Call with too few input arguments

任何帮助将不胜感激！

Any help would be much appreciated!

推荐答案

来自 Value.Call documentation :

Call使用输入参数in调用函数v.例如，如果len(in) == 3，则v.Call(in)表示Go调用v(in[0], in[1], in[2]).

Call calls the function v with the input arguments in. For example, if len(in) == 3, v.Call(in) represents the Go call v(in[0], in[1], in[2]).

因此，如果要使用一个参数调用函数，则in必须包含一个reflect.Value 正确的类型，以您的情况为map[string][]string.

So if you want to call a function with one parameter, in must contain one reflect.Value of the right type, in your case map[string][]string.

表达式

in := make([]reflect.Value,0)

创建一个长度为0的切片.将其传递给Value.Call会导致您在收到恐慌时 需要1个参数，而不是零.

creates a slice with length 0. Passing this to Value.Call will result in the panic you receive as you need 1 parameter, not zero.

正确的呼叫应该是:

m := map[string][]string{"foo": []string{"bar"}}

in := []reflect.Value{reflect.ValueOf(m)}

myMethod.Call(in)

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