How Can I Perform Dynamic Type Casting in Go with Unknown Types?

Dynamic Type Casting in Go

In Go, assigning the value of an interface to a typed variable requires knowledge of the variable's type. However, what if the type is unknown beforehand?

The conventional casting method involves a hard-coded type cast, such as:

var intAge = interfaceAge.(int)

To address the scenario where the type is unknown, some developers may propose the following:

var x = getType()
var someTypeAge = interfaceAge.(x)

However, this is not feasible in Go. The language is statically typed, meaning variable types are determined at compile time.

Alternative Approach: Type Switching

To dynamically determine the type of an interface{}, type switching can be employed:

var t interface{}
t = functionOfSomeType()
switch t := t.(type) {
default:
    fmt.Printf("unexpected type %T", t)       // %T prints the type of t
case bool:
    fmt.Printf("boolean %t\n", t)             // t has type bool
case int:
    fmt.Printf("integer %d\n", t)             // t has type int
case *bool:
    fmt.Printf("pointer to boolean %t\n", *t) // t has type *bool
case *int:
    fmt.Printf("pointer to integer %d\n", *t) // t has type *int
}

This approach allows for the dynamic identification of the type of an interface{} and subsequent type-specific handling.

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