Just create a slice of GoNoGoer
var evals []GoNoGoer
now you DO NOT need a type assertion like that
if ok := eval.(GoNoGoer); ok // REMOVE that line
Le mercredi 30 novembre 2016 17:59:07 UTC+1, sc28 a écrit :
>
> I'm trying to better understand how to properly use interfaces and created
> this scenario:
>
> Let's say I have an 'evaluator' program, that over time will want to add
> more and more evaluations of a Go-NoGo nature (Nasa?)
>
> Here's want I was trying:
>
> // My Go-NoGo interface - method should return true/false and an error is
> false
> type GoNoGoer interface {
> Eval() (bool, error)
> }
>
>
> Here's a couple of concrete evaluation types:
> ----------
>
> type Evaluation1 struct {
> Data string
> }
>
> func (a *Evaluation1) Eval() (bool, error) {
> isOk := a.DoMyEvaluationWithTheData()
> if !isOk {
> return false, fmt.Errorf("evaluation failed because ...")
> }
> return true, nil
> }
>
> type Evaluation2 struct {
> SomeData string
> MoreData int64
> }
>
> func (a *Evaluation2) Eval() (bool, error) {
> isOk := a.DoMyEvaluationWithTheStructData()
> if !isOk {
> return false, fmt.Errorf("evaluation failed because ...")
> }
> return true, nil
> }
>
> ----------
>
> In main - iterate over all the evaluations and print the results of Eval()
>
> func main() {
> one := Evaluation1{Data: "abcabcabc"}
> two := Evaluation2{SomeData: "xyzxyz", MoreDate: 128}
>
> var evals []interface{} <------ So I want a slice of evaluations
> (all implemented as various structs) - probably not correct to use
> interface{}???
> evals = append(evals, one)
> evals = append(evals, two)
>
> // range over the slice, and if the object has implemented the Eval()
> method execute it and print the results (doesn't work)
> for _, eval := range evals {
> if ok := eval.(GoNoGoer); ok { <-- This also is wrong, I want to go
> the other direction (from concrete to interface)
> isOk, err := eval.Eval()
> fmt.Println(ok, err)
> }
> }
> }
>
>
> I'd appreciate the slap across the head pointing out where I'm missing the
> boat!
>
> TIA
>
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