You'd just want to have your types implement the interface for Reply, and provide a method with the same signature that clients can use.
Here's what I think you want, written in (as far as I am able to) idiomatic Go:
Here's what I think you want, written in (as far as I am able to) idiomatic Go:
That strikes me as terribly unmaintainable.
Yes, if you want it to actually be a Reply, it has to implement Reply.
That's acres of template code being duplicated all over the place
No, if you need to reuse code you can use other techniques like embedding (not shown in examples).
The features and restrictions differ from many other OO languages but I think the creators of Go deserve a little more credit than you are giving them - they do not produce unmaintainable code (see std lib for Go), worked on a large scale with C++ OOP previously, designed the forking Unix operating system, and are not unaware of the ramifications of the decisions taken.
Maybe I don't know what exactly you want.
The Foo and Bar in my example have quite different CheckStatus() methods because those two structs are quite different. If there were more similar, then you could share more code.