What's the best practice to infer the methods?

Question

I have a custom time format which I use to properly encode/decode json. However whenever I need to do a time computation I need to do a cast. Is this the right way? It feels a b

Answer 1

Presumably you have type Mytime time.Time. If instead you embedded it:

type MyTime struct {
        time.Time
}

Then you could have:

func (t MyTime) MarshalJSON() ([]byte, error) {
        … whatever …
}

and still access all of time.Time's methods. E.g. something like:

        t := MyType{time.Now()}
        t.Time = t.Add(time.Hour)

---

Fuller example showing differences between embedded and non-embedded custom time types. Note that embedding still doesn't allow for transparent inter-use with things that expect a time.Time value. (The reason for making these types, e.g. to add a MarshalJSON method has been omitted here).

package main

import (
    "fmt"
    "time"
)

type YourTime time.Time

type MyTime struct{ time.Time }

// Some random functions, perhaps in a third party package,
// that deals with time.Time values.
func fn(t time.Time) {
    fmt.Println("fn got:", t)
}

func fn2() time.Time {
    return time.Unix(14e8, 0)
}

func main() {
    var t1 = YourTime(time.Now())
    //t1 = t1.Add(time.Hour)             // compiler error
    t1 = YourTime(time.Time(t1).Add(time.Hour))
    fmt.Println("ugly t1:", t1)
    fmt.Println("nice t1:", time.Time(t1))
    //fn(t1)                        // compiler error
    fn(time.Time(t1))

    //t1 = fn2()                    // compiler error
    t1 = YourTime(fn2())

    var t2 = MyTime{time.Now()}
    // t2 = t2.Add(time.Hour)       // compiler error
    t2.Time = t2.Add(time.Hour)
    fmt.Println("t2:", t2)
    //fn(t2)                        // compiler error
    fn(t2.Time)

    //t2 = fn2()                    // compiler error
    t2.Time = fn2()
}

Playground

Output:

ugly t1: {63393494400 0 0x1c9340}
nice t1: 2009-11-11 00:00:00 +0000 UTC
fn got: 2009-11-11 00:00:00 +0000 UTC
t2: 2009-11-10 23:00:00 +0000 UTC
fn got: 2009-11-10 23:00:00 +0000 UTC