Thanks rog for the suggestions. I can see the case for mocking as well.
On Tuesday, December 13, 2016 at 5:11:26 AM UTC-8, rog wrote:
>
> On 13 December 2016 at 01:08, go-question <question....@gmail.com
> <javascript:>> wrote:
> >
> > I noticed that its possible to define/scope types/interfaces in
> functions.
> >
> > Now I'm not arguing that this is good practice, but for the sake of
> > curiosity.
> > How can I then add a method w/ a receiver to type foo so that it
> satisfies
> > interface ifoo? (in function scope)
> >
> >
> > func main() {
> >
> > type foo struct{
> > a string
> > }
> >
> > type ifoo interface {
> > Bar()
> > }
> >
> > // possible?
> > foo{"baz"}.Bar()
> >
> > }
>
> Technically you can do it (you can make a program that will compile,
> demonstrating that your type does satisfy the interface)
> but it's not very useful because it'll crash when you call the method :-)
>
> package main
>
> func main() {
> type ifoo interface {
> Bar()
> }
> type foo struct {
> ifoo
> a string
> }
> // Yup, it's possible, but it's probably not what you want.
> foo{a: "baz"}.Bar()
> }
>
>
> This is still a useful technique in some circumstances though (for example
> if there's a large interface that I want to mock only a small portion of,
> I can embed the interface and define only those methods I expect to be
> called).
>
> Another useful technique when you want function-scoped methods is this:
>
> package main
>
> import "fmt"
>
> type ifoo interface {
> Bar()
> }
>
> type ifooFuncs struct {
> bar func()
> // ... and another function-typed field for each method.
> }
>
> func (f ifooFuncs) Bar() {
> f.bar()
> }
>
> func main() {
> x := ifooFuncs{
> bar: func() {
> fmt.Println("bar")
> },
> }
> x.Bar()
> }
>
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