How Can I Create Objects of a Specific Type within a Generic Function in Go 1.18?

Creating Objects Using Typed Generics in Go 1.18

In Go 1.18, generics allow the creation of functions that work with any data type. However, creating a new object of a specific type within a generic function requires specific syntax.

Implementing the Create Function

For example, consider a function "Create" that should create a new instance of the struct "Apple." To achieve this in generics:

type FruitFactory[T any] struct{}

func (f FruitFactory[T]) Create() *T {
    // How to create non-nil fruit here?
    return nil // Placeholder, don't return nil
}

type Apple struct {
    color string
}

Approach 1: Using a Type Variable

If "Apple" is not a pointer type, a typed variable can be declared and its address returned:

func (f FruitFactory[T]) Create() *T {
    var a T // Declare variable of type T
    return &a // Return address of variable
}

Approach 2: Using the "new" Function

Alternatively, the "new" function can be used to create a new object:

func (f FruitFactory[T]) Create() *T {
    return new(T)
}

Handling Pointer Types

In case "FruitFactory" is instantiated with a pointer type, a more involved approach is necessary:

// Constraining type to its pointer type
type Ptr[T any] interface {
    *T
}

// Type parameters: FruitFactory (pointer type), FruitFactory (non-pointer type)
type FruitFactory[T Ptr[U], U any] struct{}

func (f FruitFactory[T,U]) Create() T {
    var a U // Declare non-pointer type variable
    return T(&a) // Convert to pointer type
}

type Apple struct {
    color string
}

By following these approaches, it is possible to create new objects of any type using generics in Go 1.18.

The above is the detailed content of How Can I Create Objects of a Specific Type within a Generic Function in Go 1.18?. For more information, please follow other related articles on the PHP Chinese website!