05.Structs_Functions_Revisited.slide

# Methods & Interfaces

## structs revisited

    Go is a statically typed language with both built-in types and user-defined types. 
    Like most modern languages, Go allows you to attach methods to types.

    Method declarations look just like function declarations, with one addition 
    the receiver specification

.code -numbers -edit code/structs_funcs_revisited/methods.go /^type Employee/,/^}/

.code -numbers -edit code/structs_funcs_revisited/methods.go /String()/,/^}/

.code -numbers -edit code/structs_funcs_revisited/methods.go /SetAge/,/^}/ 

## 

.play -numbers -edit code/structs_funcs_revisited/methods.go /^func main/,/^}/

## Use Embedding for Composition

.play -numbers -edit code/structs_funcs_revisited/embed.go /^func main/,/^}/

## Interfaces
    - Go's interfaces special is that they are implemented implicitly
    - An empty interface can hold values of any type since every type implements at least zero methods. 

.play -numbers -edit code/structs_funcs_revisited/interface.go /^func main/,/^}/

## Iterfaces cont...
    - An interface type is defined as a set of method signatures.
    - A value of interface type can hold any value that implements those methods.

.code -numbers -edit code/structs_funcs_revisited/interface_type.go /^type Printer/,/^}/

.code -numbers -edit code/structs_funcs_revisited/interface_type.go /^type Employee/,/^}/

.code -numbers -edit code/structs_funcs_revisited/interface_type.go /^type Printer/,/^}/

.code -numbers -edit code/structs_funcs_revisited/interface_type.go /^func \(e Employee\) Print/,/^}/

.code -numbers -edit code/structs_funcs_revisited/interface_type.go /^func \(p Person\) Print/,/^}/

##

.code -numbers -edit code/structs_funcs_revisited/interface_type.go /^func Print/,/^}/

.play -numbers -edit code/structs_funcs_revisited/interface_type.go /^func main/,/^}/