[Go: Ellipsis, JSON/Unmarshalling] #go #golang #ellipsis #json #pointers

tips.go

// vim: syntax=go

// ***** 3 PERIODS (ELLIPSIS) UNPACK A VARIABLE *****
primes := []int{2, 3, 5, 7}  
fmt.Println(Sum(primes...)) // 17


// ***** JSON STRUCTS *****
// A field with a json: struct tag is stored with its tag name instead of its variable name.  
type user struct {
        ID int `json: "ref"`
        name string
        name2 string `json: "name2"`
}
// When `json.Marshal` is run ID is put as a `ref` key in json.
// However, `name` will not be put in the json because it is lowercase and therefore not exported.
// But, because `name2` has a declared json field it does get exported. 

// ***** POINTERS & REFERNCING/DEREFERENCING *****
// `&` is a pointer --> `b = &a` == memory address of a
// `*` gets the pointers underlying value, aka "dereferencing" --> `*b` gives the values in the memory of a
// `func (c *Config) Read(p string) {}` --> c is a pointer receiver, meaning &c changes the actual values of the config struct