英文:
Declare a function type with an arbitrary return type in golang
问题
我是你的中文翻译助手，以下是翻译好的内容：
我刚开始学习Go语言，遇到了一个问题，在教程和谷歌搜索中都没有找到相关的解答，但我相信这一定是我错过的语言基础知识。我有以下的代码：
type Task func()
var f Task = func() { fmt.Println("foo") }
type TaskWithValue func() interface{}
var g TaskWithValue = func() { return "foo" }
var h TaskWithValue = func() { return 123 }
在上面的代码中，f没有编译错误，但是对于g和h，会出现以下错误：
Cannot use func() { return "foo" } (type func()) as type TaskWithValue in assignment
实际上，我想定义一个Task类型，它可以具有任意的返回类型。在其他语言中，我可以简单地给Task添加一个类型参数，比如Task<Integer>或Task<String>，但是由于Go语言没有泛型/模板，我了解到的解决方法是使用返回类型interface{}，然后进行类型转换。请问我在这个例子中漏掉了什么？
英文:
I'm new to go and have come across the following issue that I haven't been able to find covered in the tutorial or google searches, though I'm sure it must be a basic aspect of the language I have missed. I have code like the following:
type Task func()
var f Task = func() { fmt.Println("foo") }
type TaskWithValue func() interface{}
var g TaskWithValue = func() { return "foo" }
var h TaskWithValue = func() { return 123 }
In f above, there is no compiler error, but for g and h there are errors like the following:
Cannot use func() { return "foo" } (type func ()) as type TaskWithValue in assignment
Essentially, I'm trying to define a Task type that can have an arbitrary return type. In other languages, I would simply give Task a type parameter, like Task<Integer> or Task<String>, but since go does not have generics/templates, I understood the workaround is to use return type interface{} and then cast the results. What am I missing to get this example working?
答案1
得分: 4
你在匿名函数表达式中缺少返回类型：
var g TaskWithValue = func() interface{} { return "foo" }
var h TaskWithValue = func() interface{} { return 123 }
英文:
You're missing the return type in the anonymous function expressions:
var g TaskWithValue = func() interface{} { return "foo" }
var h TaskWithValue = func() interface{} { return 123 }
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