You would typically define the array type as an array of some interface
that is implemented by both purchase and coupon. You can then use a
type-switch or type-assertion to determine/assert the actual type at
runtime, on a per element basis.
If the two types do not share some interface (e.g. common methods), you
could define the array as []interface{}. But this also allows code to
accidentally add *any* kind of value to the array (not just a purchase or a
coupon). So it may be better to create a marker interface -- an unexported
interface with a no-op unexported marker method -- and make purchase and
coupon both implement that interface.
For example:
type checkoutObject interface {
checkoutObject()
}
type Purchase struct {
// yadda yadda
}
func (p *Purchase) checkoutObject() {
// no-op marker method
}
type Coupon struct {
// yadda yadda
}
func (c *Coupon) checkoutObject() {
// no-op marker method
}
// assert that Purchase and Coupon implement checkoutObject
var _ checkObject = (*Purchase)(nil)
var _ checkObject = (*Coupon)(nil)
*// Now you can define your array like so:*
*var checkoutItems []checkoutObject*
*// The compiler will only let you add *Purchase and *Coupon*
*// values to the array.*
*// You can use the values at runtime like so:*
*for e := range checkoutItems {*
*switch e := e.(type) {*
*case *Purchase:*
*// handle purchase*
*case *Coupon:*
*// handle coupon*
*default:*
*panic(fmt.Sprintf("unsupported type: %T", e))*
*}*
*}*
*Josh Humphries*
jh...@bluegosling.com
On Thu, Jan 4, 2018 at 10:24 AM, Tong Sun wrote:
> I need a data struct / solution that I can store mixed data-types into an
> array. How to architect that?
>
>
> Details -- Consider the checkout point at the cashier, the checkout
> process receives the following string of instructions
>
>1. purchase
>2. coupon
>3. purchase
>4. purchase
>
> I want to store all the above request data into an array, so I don't lost
> the sequence how they arrive, which in turn requests the array element to
> be either purchase or coupon.
>
>
> How to make it happen? Thanks
>
>
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