I have this problem which seems a bit weird to me. Take a look at this snippet of code:
package coreinterfaces
type FilterInterface interface {
Filter(s *string) bool
}
type FieldFilter struct {
Key string
Val string
}
func (ff *FieldFilter) Filter(s *string) bool {
// Some code
}
type FilterMapInterface interface {
AddFilter(f *FilterInterface) uuid.UUID
RemoveFilter(i uuid.UUID)
GetFilterByID(i uuid.UUID) *FilterInterface
}
type FilterMap struct {
mutex sync.Mutex
Filters map[uuid.UUID]FilterInterface
}
func (fp *FilterMap) AddFilter(f *FilterInterface) uuid.UUID {
// Some code
}
func (fp *FilterMap) RemoveFilter(i uuid.UUID) {
// Some code
}
func (fp *FilterMap) GetFilterByID(i uuid.UUID) *FilterInterface {
// Some code
}
On some other package, I have the following code:
func DoFilter() {
fieldfilter := &coreinterfaces.FieldFilter{Key: "app", Val: "152511"}
filtermap := &coreinterfaces.FilterMap{}
_ = filtermap.AddFilter(fieldfilter) // <--- Exception is raised here
}
The run-time won't accept the line mentioned because
"cannot use fieldfilter (type *coreinterfaces.FieldFilter) as type *coreinterfaces.FilterInterface in argument to fieldint.AddFilter: *coreinterfaces.FilterInterface is pointer to interface, not interface"
However, when changing the code to:
func DoBid() error {
bs := string(b)
var ifilterfield coreinterfaces.FilterInterface
fieldfilter := &coreinterfaces.FieldFilter{Key: "app", Val: "152511"}
ifilterfield = fieldfilter
filtermap := &coreinterfaces.FilterMap{}
_ = filtermap.AddFilter(&ifilterfield)
}
Everything is alright and when debugging the application it really seems to include
I'm a bit confused on this topic. When looking at other blog posts and stack overflow threads discussing this exact same issue (for example - This, or This) the first snippet which raises this exception should work, because both fieldfilter and fieldmap are initialized as pointers to interfaces, rather than value of interfaces. I haven't been able to wrap my head around what actually happens here that I need to change in order for me not to declare a FieldInterface and assign the implementation for that interface. There must be an elegant way to do this.