How to Handle Default Values for Generic Types in Go?

Default Value for Generic Types

Returning nil for any type is not allowed in Go. Even for generic types, where T could represent any type, nil is not a valid option. Types like structs and integers don't have a nil representation.

Instead, the zero value for the specific type argument used for T can be returned. The zero value varies depending on the type:

• Nil for pointers and slices
• Empty string for strings
• 0 for integers and floats

To return the zero value, declare a variable of type T and return it:

func getZero[T any]() T {
    var result T
    return result
}

For example, using the getZero function:

i := getZero[int]()
fmt.Printf("%T %v\n", i, i) // Output: int 0

s := getZero[string]()
fmt.Printf("%T %q\n", s, s) // Output: string ""

p := getZero[image.Point]()
fmt.Printf("%T %v\n", p, p) // Output: image.Point (0,0)

f := getZero[*float64]()
fmt.Printf("%T %v\n", f, f) // Output: *float64 <nil>

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