去反射一下。 如何返回err = nil作为reflect.Value？
问题描述：
How to return a err=nil as reflect.Value? I need to write a swap function to use with reflect.MakeFunc().
//my swap implementation, that call the original function and cache results
func swapFunc(ins []reflect.Value) []reflect.Value {
//After cache the first return (Offer) of function FindBestOffer(int)(Offer,bool,error),
//i need to return the best Offer cached and default values
//for the two other returns (bool=true, err=nil)
outs := make([]reflect.Value, 3) //mock cache return
outs[0] = reflect.ValueOf(Offer{10, "cached offer", 20})
outs[1] = reflect.ValueOf(true)
outs[2] = reflect.ValueOf(nil).Elem() // --> Doesn't work!
return outs
}
答
It's tricky, you have to use reflect.Zero:
out[2] = reflect.Zero(reflect.TypeOf((*error)(nil)).Elem())
答
Defining a typed nil error works too...
var err error = nil
outs[2] = reflect.ValueOf(&err).Elem()
Just out of curiosity. Go Playground