[Feature]: generic Conn context

[rdmrcv]

Description of new feature

Would be great if the Conn was a generic interface.

Like:

// ConnG is a generic interface of underlying connection.
type ConnG[Ctx any] interface {
	Reader
	Writer
	Socket

	// ================================== Non-concurrency-safe API's ==================================

	// Context returns a user-defined context.
	Context() (ctx Ctx)

	// SetContext sets a user-defined context.
	SetContext(ctx Ctx)
	...
}

// Conn is an interface that provide a most general Conn interface with an `interface{}` context.
type Conn ConnG[any]

This'll allow users avoid many conversions (and many small allocs) when context used.

This is a breaking change, but in soft manner. Since you can maintain the ConnG and the Conn separately and the Conn will be almost identical to current Conn that use interface{} to a context.
You can get incompatibility here, but mostly in advanced use-cases when some tool rely on the Conn internal representation.

Also, the change will require the golang version bump to 1.18. You can also maintain compatibility if you leave the original Conn implementation and guard it via build tags.

Scenarios for new feature

• For those who do not use context — nothing changes. They'll still use Conn and nothing should changes for them.
• For those who use an interface{} as Context. Same as above.
• For those who want use own context - nothing changes except elimination all of the conversions from an interface{} to the own type.

Breaking changes or not?

Yes

Code snippets (optional)

No response

Alternatives for new feature

None.

Additional context (optional)

Good example of same change can be found here.

[someview]

这个应该不太好做。需要兼容go原生的context

[xsean2020]

// import "context"
//
// // User is the type of value stored in the Contexts.
// type User struct {...}
//
// // key is an unexported type for keys defined in this package.
// // This prevents collisions with keys defined in other packages.
// type key int
//
// // userKey is the key for user.User values in Contexts. It is
// // unexported; clients use user.NewContext and user.FromContext
// // instead of using this key directly.
// var userKey key
//
// // NewContext returns a new Context that carries value u.
// func NewContext(ctx context.Context, u *User) context.Context {
// return context.WithValue(ctx, userKey, u)
// }
//
// // FromContext returns the User value stored in ctx, if any.
// func FromContext(ctx context.Context) (*User, bool) {
// u, ok := ctx.Value(userKey).(*User)
// return u, ok
// }
估计只能用go 目前推荐的方式