Thanks
On Wednesday, November 30, 2016 at 2:05:59 PM UTC-5, parais...@gmail.com
wrote:
>
> 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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