Abstraction patterns in go

Question

I have two interfaces. They are almost the same, the only difference is the Set method:

type Cache1 interface {
    Set(key, value interface{}, ttl time.Duration) bool
}

type Cache2 interface {
    Set(key, value interface{}) bool
}

Any idea how to unite them into one abstraction? Surely I can add ttl time.Duration to the second interface, but it will useless there and will worsen code readability. Could you please suggest sophisticated pattern if such exist?

There's no way to answer this question. The proper solution depends on countless variables. How are you using these interfaces? Why do they need to be the same interface in the first place? How are they used? Should `Set` even be part of the interface? Etc etc. Without an intimate understanding of your application, there's no way to answer this. — Jonathan Hall, Mar 05 '18 at 13:46
Do you want to keep both methods? Or you want a single, merged `Set()` method? — icza, Mar 05 '18 at 13:46
@Rudziankoŭ Then that comes down to [Optional Parameters?](https://stackoverflow.com/questions/2032149/optional-parameters) — icza, Mar 05 '18 at 13:50

score 3 · Accepted Answer · edited Mar 05 '18 at 14:03

3

I guess, you should care of interface segregation principle while merging those methods.

Technically, you are able to merge them by wrapping all arguments to SetRequest or something. Interface will be sort of

type Cache interface {
    Set(request SetRequest) bool
}

edited Mar 05 '18 at 14:03

Jonathan Hall

75,165
16
143
189

answered Mar 05 '18 at 13:51

Ivan Rubanau

374
2
12

score 0 · Answer 2 · answered Mar 05 '18 at 14:08

Another opportunity just came in mind is unite interfaces into one:

type Cache interface {
    Set(key, value interface{}, ttl time.Duration) bool
}

And ignore redundant argument in method signature if necessary:

func (c *cache) Set(key, value interface{}, _ time.Duration) bool {

Abstraction patterns in go

2 Answers2