Optional implementation for GoLang
The given code is an implementation of optional values in Go using generics. It defines a generic type Optional[T] which can hold an optional value of any type T.
The Optional[T] struct holds two fields:
The Some[T any](obj T) Optional[T] function creates a new Optional[T] instance with the provided non-null value obj. It first checks if obj is nil. If it is, it throws a panic indicating that a null reference was passed. Otherwise, it returns a new Optional[T] instance with val set to obj.
The None[T any]() Optional[T] function returns a new Optional[T] instance without a value or error. It simply returns an instance that holds no value.
The Error[T any](err error) Optional[T] function creates a new Optional[T] instance with the provided error value err. It checks if the err parameter is nil and throws a panic if so. Otherwise, it returns a new Optional[T] instance with err set to the provided value.
The IsNone() method checks if the optional value is empty.
The IsSome() method checks if the optional value is not empty.
The HasError() method checks if the optional value contains an error by checking if the err field is not nil.
The Get() method returns the value held by the optional. It throws a panic if the value has not been set.
The GetError() method returns the error held by the optional. It throws a panic if the error is not set.
opt := gooptional.Some[int](5)
opt.IsSome() //returns true
opt.IsNone() //returns false
opt.HasError() //returns false
val := opt.Get() // assign the value 5 to val
opt.GetError() //this will panic
opt2 := gooptional.None[int]()
opt2.IsSome() //returns false
opt2.IsNone() //returns true
opt2.HasError() //returns false
opt3 := gooptional.Error[int]()
opt3.IsSome() //returns false
opt3.IsNone() //returns true
opt3.HasError() //returns true
err := opt3.GetError() //assign the error to err
var *int i
opt4 := gooptional.Some(i) //this will panic