How do I STORE different structs in a slice or a struct in Go (Not embedding)

Question

I am new to Golang, after I took a tour of A Tour of Go, I'm trying to make my own thing.

What I want

I want to put different types of the structs into a single slice (or struct?),

so I can use a for loop to pass each struct to a function.

For example

In PHP I can store my classes in an array and pass each of them to foobar() like this:

$classes = [$A, $B, $C, $D]; // $A, $B, $C, $D are classes (called `struct` in Golang). foreach ($classes as $class) foobar($class);

What I tried

I tried to do the same in Golang, and I hope it looks like this:

A{B{}, C{}, D{}}

Since I failed on using slice, I decided to use struct to hold my structs:

type A struct { B C D } type B struct { Date string } type C struct { Date string } type D struct { Date string } func main() { // Using reflect to loop the A struct: // http://stackoverflow.com/questions/18926303/iterate-through-a-struct-in-go v := reflect.ValueOf(A{}) for i := 0; i < v.NumField(); i++ { foobar(v.Field(i).Interface()) // Passing each struct to the `foobar()` function } }

But it seems like I'm actually doing embedding instead of storing them, any suggestions please?

Seva · Accepted Answer · 2016-10-01 01:16:03Z

I think interface{} is what you're after. For example like this:

type A struct { data string } type B struct { data int } func printData(s interface{}) { switch s.(type) { case A: fmt.Printf("A: %s\n", s.(A).data) case B: fmt.Printf("B: %d\n", s.(B).data) } } func main() { classes := []interface{}{A{data: "first"}, B{data: 2}, A{data: "third"}} for _, c := range classes { printData(c) } }

This is probably as close as you can get to "duck typing" in go.

Though if your structs are really that similar, you might better off defining a common interface instead and implementing that interface for each struct. Here is same example using interfaces:

type DataGetter interface { getDate() string } type A struct { data string } func (a A) getDate() string { return a.data } type B struct { data int } func (b B) getDate() string { return fmt.Sprintf("%d", b.data) } func printData(s DataGetter) { fmt.Printf("%s\n", s.getDate()) } func main() { classes := []DataGetter{A{data: "first"}, B{data: 2}, A{data: "third"}} for _, c := range classes { printData(c) } }

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How do I STORE different structs in a slice or a struct in Go (Not embedding)

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