结合了数据和功能以及接口和结构的组合

Question

I'm wondering if this is something that's done in Go or if I'm thinking about it all wrong: composing type x interface and type x struct so my interface methods have access to specific data too:

The C programmer in my wants to do this:

type PluginHandler interface {
    onLoad()
    pm *PluginManager
}
func (ph PluginHandler) onLoad() {
    pm.DoSomething()
}

There I have an interface defined with a function, but also some data I want to pass to those functions but this is a syntax error.

So is this something that's doable in Go through some other method or am I just thinking about the problem wrong?

Answer 1

You have defined onLoad incorrectly. You cannot define a function directly on interface type.

Once you have an interface, you need another type to implement methods specified in the interface. For example, if another type implements onLoad method, they automatically (implicitly) implement the interface PluginHandler.

The other thing you need to do is change the interface function type to accept the required data:

type PluginHandler interface {
    onLoad(*PluginManager)
}

struct SomeType {
    // ...
}

func (s SomeType) onLoad(pm *PluginManager) { // SomeType now implements
    pm.DoSomething()                          // PluginHandler interface.
}

This way, you get to inject whichever PluginManager required by PluginHandler.

Also, you can use SomeType as a PluginHandler type whereever required.

func someFuntion(ph PluginHandler) {
    // ...
    ph.onLoad(pm)
    // ...
}

Can be called with an input argument of type SomeType:

s := SomeType{}
someFunction(s)