Learning Go Language – Day 3

Maps

- Collections of value types that are access via keys
- Created via literals or via "make" function
- Creation syntax:
  - name = map[type]type()
  - Alt creation = make(map[type]type)
- Members accessed via [key] syntax and .dot syntax
  - myMap["key"] = "value"
  - myMap.value
- Check for presence with "value, ok" form of result
- Multiple assignments refer to same underlying data

// Example code
func main() {
  statePopulations := map[string]int {
		"California": 1,
		"Texas": 2,
		"Florida": 3,
		"New York": 4,
		"Pennsylvania": 5,
		"Illinois": 6,
		"Ohio": 7,
	}
	fmt.Println(statePopulations)
}
// NOTE: The types must be support the ability for equality

Structs

- You can mix-and-match datatypes in structs, unlike in other types like arrays
- Naming convention is the same: PascalCase for export, camelCase for import
- Keyed by named field
- Normally created as types, but anonymous structs are possible
- Structs are value types, meaning copying them will make a new struct
- No inheritance, but can use composition via embedding
- Tags can be added to struct fields to describe fields
- If there is no data in a certain field, you can ignore that field in the struct entirely

// Example code
type Doctor struct {
  number int
  actorName string
  companions []string
}

func main() {
  aDoctor := Doctor {
  number: 3,
  actorName: "Jon Pertwee",
  companions: []string {
    "Liz Shaw",
    "Jo Grant",
    "Sarah Jane Smith",
    },
  }
  fmt.Println(aDoctor)
}