Golang Variadic Constructor Function? Create a Person Contact in Golang?

Question

I am making a contact application for learning. I have a NewContact().

// Contact - defines the fields of an entire Contact
type Contact struct {
    Title     string
    FirstName string
    LastName  string
    HomePhone string
    WorkPhone string
    Mobile    string
    Address   *Address
    Email     string
}    
// NewContact - Creates a new contact
func NewContact(first string, last string) *Contact {
    c := &Contact{}
    c.FirstName = first
    c.LastName = last

    return c

}

This does work however....I can require a FirstName and LastName BUT how would I make ALL the other field arguments optional? Thank you in advance.

Answer 1

Only your use case, domain and the design can tell which approach is preferable. But you can:

1 - Use chaining methods:

func main() {
    c := new(Contact)
    c = c.SetEmail("...").SetFirstName("...").SetLastName("...")
}

type Contact struct {
    Title     string
    FirstName string
    LastName  string
    HomePhone string
    WorkPhone string
    Mobile    string
    Address   *Address
    Email     string
}

func (c *Contact) SetTitle(v string) *Contact     { c.Title = v; return c }
func (c *Contact) SetFirstName(v string) *Contact { c.FirstName = v; return c }
func (c *Contact) SetLastName(v string) *Contact  { c.LastName = v; return c }
func (c *Contact) SetHomePhone(v string) *Contact { c.HomePhone = v; return c }
func (c *Contact) SetWorkPhone(v string) *Contact { c.WorkPhone = v; return c }
func (c *Contact) SetMobile(v string) *Contact    { c.Mobile = v; return c }
func (c *Contact) SetAddress(v *Address) *Contact { c.Address = v; return c }
func (c *Contact) SetEmail(v string) *Contact     { c.Email = v; return c }

2 - Use functional options:

func main() {
    c := NewContact(FirstName("..."), LastName("..."))
    _ = c
}

type Contact struct {
    Title     string
    FirstName string
    LastName  string
    HomePhone string
    WorkPhone string
    Mobile    string
    Address   *Address
    Email     string
}

func NewContact(options ...ContactOption) *Contact {
    c := new(Contact)
    for _, opt := range options {
        opt(c)
    }
    return c
}

type ContactOption func(*Contact)

func Title(v string) ContactOption        { return func(c *Contact) { c.Title = v } }
func FirstName(v string) ContactOption    { return func(c *Contact) { c.FirstName = v } }
func LastName(v string) ContactOption     { return func(c *Contact) { c.LastName = v } }
func HomePhone(v string) ContactOption    { return func(c *Contact) { c.HomePhone = v } }
func WorkPhone(v string) ContactOption    { return func(c *Contact) { c.WorkPhone = v } }
func Mobile(v string) ContactOption       { return func(c *Contact) { c.Mobile = v } }
func SetAddress(v *Address) ContactOption { return func(c *Contact) { c.Address = v } }
func Email(v string) ContactOption        { return func(c *Contact) { c.Email = v } }