Design-Patterns on maladroit.dev

Design Patterns

Mon, 01 Jan 0001 00:00:00 +0000

Design Patterns

Functional options pattern

Mon, 01 Jan 0001 00:00:00 +0000

Functional options pattern

Using closures to build up optional parameters.

Example

type (
 options struct {
 port *int
 }

 Option func(*options) error
)

func WithPort(port int) Option {
 return func(options *options) error {
 if port < 0 {
 return errors.New("port less than zero")
 }

 options.port = &port
 return nil
 }
}

func NewServer(add string, opts ...Option) (*http.Server, error){
 var options options
 for _, opt := range opts {
 err := opt(&options)
 if err != nil {
 return nil, err
 }
 }
 // remaining implementation
}

References

100-go-mistakes-and-how-to-avoid-them

Index as hash key

Mon, 01 Jan 0001 00:00:00 +0000

Index as hash key

In scenarios where space needs to be preserved and a hash table cannot be used, it is possible to use an array instead.

For example, given an array of 1 to N values where N is the length of the array. The value in the array can be negated to indicate presence.