英文:
How to convert from `func() *int` to `func() interface{}`?
问题
我想要一个类似以下函数的东西：
func decorateFn(fn func() interface{}) interface{} {
decorate()
return fn()
}
func decorateFnInt(fn func() *int) *int {
return decorateFn(fn).(*int)
}
使用 decorateFn((func() interface{})(fn)).(*int) 是不起作用的。是否可能将 func() *int 转换为 func() interface{}？如果可以，应该如何转换？
英文:
I'd like to have something like the following function:
func decorateFn(fn func() interface{}) interface{} {
decorate()
return fn()
}
func decorateFnInt(fn func() *int) *int {
return decorateFn(fn).(*int)
}
Using decorateFn((func() interface{})(fn)).(*int) doesn't work. Is it possible to convert func() *int to func() interface{}? If so, how?
答案1
得分: 4
使用go 1.18，你可以使用泛型来实现这一点-确保在编译时进行类型安全检查，而无需运行时类型断言：
func decorateFn[T any](fn func() T) T {
decorate()
return fn()
}
func decorateFnInt(fn func() *int) *int {
return decorateFn(fn)
}
函数decorateFn的类型约束可以通过检查fn的类型在编译时推断出来。
链接：https://go.dev/play/p/AAByiBFRQch
编辑：如果你被困在go 1.17并且无法使用泛型，你可以使用interface{}作为函数参数，但是任何类型决策都必须在运行时执行。你可以尝试使用类型切换：
func decorateFn(v interface{}) interface{} {
decorate()
switch t := v.(type) {
case func() *int:
return t()
case func() *string:
return t()
default:
panic(fmt.Sprintf("unsupported type: %T", v))
}
}
链接：https://go.dev/play/p/gDXTPqA1tXL
英文:
With go 1.18 you can use generics to achieve this - ensuring compile-time type safety and no runtime type assertions:
func decorateFn[T any](fn func() T) T {
decorate()
return fn()
}
func decorateFnInt(fn func() *int) *int {
return decorateFn(fn)
}
The function decorateFn's type constraint can be inferred at compile-time by inspecting fn's type.
https://go.dev/play/p/AAByiBFRQch
EDIT: if you are stuck on go 1.17 and cannot use generics, you can use interface{} for the function parameter, but any type decisions must be performed at runtime. You could try a type switch:
func decorateFn(v interface{}) interface{} {
decorate()
switch t := v.(type) {
case func() *int:
return t()
case func() *string:
return t()
default:
panic(fmt.Sprintf("unsupported type: %T", v))
}
}
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