A library that provides Go Generics friendly "optional" features.
database/sql/driver.Valuer and database/sql.Scanner on Option type #30UnwrapAsPtr() method to unwrap the Option value as a pointer #28UnwrapAsPtr #31#OrElse() function #22This feature changes the method signature of the #OrElse() that was introduced by v0.9.0, becoming to take a function that provides the fallback optional value. And the old implementation has been renamed #Or().
FromNillable() and PtrFromNillable() #18These methods accept the nillable pointer value as an argument and make the Optional[T] type value.
FromNillable()If the given value is not nil, this returns Some[T] value with doing value-dereference.
On the other hand, if the value is nil, this returns None[T].
example:
num := 123
some := FromNillable[int](&num)
fmt.Printf("%v\n", some.IsSome()) // => true
fmt.Printf("%v\n", some.Unwrap()) // => 123
none := FromNillable[int](nil)
fmt.Printf("%v\n", none.IsSome()) // => false
fmt.Printf("%v\n", none.Unwrap()) // => 0 (the default value of int)
PtrFromNillable()If the given value is not nil, this returns Some[*T] value without doing value-dereference.
On the other hand, if the value is nil, this returns None[*T].
example:
num := 123
some := PtrFromNillable[int](&num)
fmt.Printf("%v\n", some.IsSome()) // => true
fmt.Printf("%v\n", *some.Unwrap()) // => 123 (NOTE: it needs doing dereference)
none := PtrFromNillable[int](nil)
fmt.Printf("%v\n", none.IsSome()) // => false
fmt.Printf("%v\n", none.Unwrap()) // => nil
omitempty option on JSON marshaling #17This version brings up the support for the omitempty option on JSON marshaling. If the property has that option and the value is None[T], it omits that property from the serialized JSON string.
example:
type JSONStruct struct {
OmitemptyVal Option[string] `json:"omitemptyVal,omitempty"` // this should be omitted
}
jsonStruct := &JSONStruct{OmitemptyVal: None[string]()}
marshal, err := json.Marshal(jsonStruct)
if err != nil {
return err
}
fmt.Printf("%s\n", marshal) // => {}
This version begins to support the following new methods:
FlatMap[T, U any](option Option[T], mapper func(v T) Option[U]) Option[U]
FlatMapOr[T, U any](option Option[T], fallbackValue U, mapper func(v T) Option[U]) U
FlatMapWithError[T, U any](option Option[T], mapper func(v T) (Option[U], error)) (Option[U], error)
FlatMapOrWithError[T, U any](option Option[T], fallbackValue U, mapper func(v T) (Option[U], error)) (U, error)
Please refer to the godoc for more details: https://pkg.go.dev/github.com/moznion/go-optional
This version begins to support the following new methods:
func (o Option[T]) IfSome(f func(v T))
func (o Option[T]) IfSomeWithError(f func(v T) error) error
func (o Option[T]) IfNone(f func())
func (o Option[T]) IfNoneWithError(f func() error) erro
Please refer to the godoc for more details: https://pkg.go.dev/github.com/moznion/go-optional