reflect.InterfaceValue does not have Implements(*reflect.InterfaceType) bool method #327
Description
by wmundt42:
There is currently no way, via the reflection interface, to do a
conditional set. Such a set would have the semantics of the two-result
type assertion in the language itself, but would allow the use of such
semantics on types passed around as variables.
Proposed semantics:
func (v *InterfaceValue) ConditionalSet(x Value) (ok bool)
{
if x implements v or x is the zero interface value {
set v to x;
returns true;
} else {
set v to zero interface value;
return false;
}
}
This would allow reflection-based checks on whether a value implements an
interface, and also (by construction of zero Value instances) whether any
reflect.Type implements a particular reflect.InterfaceType without having
to iterate the methods and evaluate the logic manually.