4 $ alias elixirc="elixirc --ignore-module-conflict" warning redefining module User (current version loaded from Elixir.User.beam) user.ex1 User alias

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1 4 NanoPlanner Elixir Elixir/Phoenix Elixir ~/elixir-primer/v02/ch04 $ mkdir -p ~/elixir-primer/v02/ch04 $ cd ~/elixir-primer/v02/ch04 ~/elixir-primer/v02 35

2 4 $ alias elixirc="elixirc --ignore-module-conflict" warning redefining module User (current version loaded from Elixir.User.beam) user.ex1 User alias 4.2 struct Elixir/Phoenix field user.ex ch04/user.ex (New) 1 defmodule User do 2 defstruct [name, ] 3 end User 36

3 4.3 2 defstruct $ elixirc user.ex Elixir.User.beam defstruct user.ex ch04/user.ex 1 defmodule User do 2 - defstruct [name, ] 2 + defstruct ["name", " "] 3 end == Compilation error on file user.ex == ** (ArgumentError) struct field names must be atoms, got "name" user.ex ch04/user.ex 1 defmodule User do 2 - defstruct ["name", " "] 2 + defstruct [name, ] 3 end 4.3 struct1.exs 37

4 4 (New) 1 m = %{name "foo", "foo@example.com"} 2 u = %User{name "foo", "foo@example.com"} 3 IO.inspect m 4 IO.inspect u Elixir $ elixir struct1.exs %{ "foo@example.com", name "foo"} %User{ "foo@example.com", name "foo"} 1 2 m = %{name "foo", "foo@example.com"} u = %User{name "foo", "foo@example.com"} 1 2 User % => struct1.exs 1 - m = %{name "foo", "foo@example.com"} 1 + m = %{name => "foo", => "foo@example.com"} 2 - u = %User{name "foo", "foo@example.com"} 2 + u = %User{name => "foo", => "foo@example.com"} Elixir struct1.exs 38

5 m = %{name => "foo", => "foo@example.com"} 1 + m = %{name => "foo", => "foo@example.com", password => "xyz"} 2 - u = %User{name => "foo", => "foo@example.com"} 2 + u = %User{name => "foo", => "foo@example.com", password => "xyz"} Elixir ** (KeyError) key password not found in %User{ "foo@example.com", > name "foo"} (stdlib) maps.update(password, "xyz", %User{ "foo@example.com" >, name "foo"}) User password user.ex 2 defstruct [name, ] defstruct password struct1.exs 1 - m = %{name => "foo", => "foo@example.com", password => "xyz"} 1 + m = %{"name" => "foo", " " => "foo@example.com"} 2 - u = %User{name => "foo", => "foo@example.com", password => "xyz"} 2 + u = %User{"name" => "foo", " " => "foo@example.com"} Elixir 39

6 4 ** (KeyError) key "name" not found in %User{ nil, name nil} (stdlib) maps.update("name", "foo", %User{ nil, name nil}) name "name" Elixir Erlang 4.4 struct1.exs (New) 1 - m = %{"name" => "foo", " " => "foo@example.com"} 1 + m = %{name "foo", "foo@example.com"} 2 - u = %User{"name" => "foo", " " => "foo@example.com"} 2 + u = %User{name "foo", "foo@example.com"} 3 - IO.inspect m 3 + IO.inspect m. 4 - IO.inspect u 4 + IO.inspect u. Elixir "foo@example.com" "foo@example.com" 3 4 IO.inspect m. IO.inspect u. m u 40

7 4.4 [ ] struct1.exs 3 - IO.inspect m. 3 + IO.inspect m[ ] 4 - IO.inspect u. 4 + IO.inspect u[ ] Elixir "foo@example.com" ** (UndefinedFunctionError) function User.fetch/2 is undefined (User does > not implement the Access behaviour) User.fetch(%User{ "foo@example.com", name "foo"}, ) 3 IO.inspect m[ ] "foo@example.com" 4 User.fetch/2 [ ] [ ] User.fetch/2 User.fetch/2 3 - IO.inspect m[ ] 3 + IO.inspect m. 41

8 4 4 - IO.inspect u[ ] 4 + IO.inspect u. 4.5 Elixir struct1.exs 1 m = %{name "foo", "foo@example.com"} 2 + m = %{m "bar@example.com"} 3 u = %User{name "foo", "foo@example.com"} 4 + u = %User{u "bar@example.com"} 5 - IO.inspect m. 5 + IO.inspect m 6 - IO.inspect u. 6 + IO.inspect u %{ "bar@example.com", name "foo"} %User{ "bar@example.com", name "foo"} 2 14 Map.merge/2 struct1.exs 42

9 4.6 1 m = %{name "foo", "foo@example.com"} 2 - m = %{m "bar@example.com"} 2 + m = Map.merge(m, %{ "bar@example.com"}) 3 u = %User{name "foo", "foo@example.com"} 4 - u = %User{u "bar@example.com"} 4 + u = Map.merge(u, %{ "bar@example.com"}) %{ "bar@example.com", name "foo"} %User{ "bar@example.com", name "foo"} Map.merge/2 2 Map.merge/ structs2.exs ch04/struct2.exs (New) 1 u = %User{ "foo@example.com"} 2 IO.inspect u.name 3 IO.inspect u. Elixir nil "foo@example.com" user.ex 43

10 4 ch04/user.ex 1 defmodule User do 2 - defstruct [name, ] 2 + defstruct [{name, "No name"}, ] 3 end user.ex structs2.exs Elixir "No name" "foo@example.com" user.ex 2 defstruct [{name, "No name"}, ] defstruct 1 name "No name" name user.ex ch04/user.ex 1 defmodule User do 2 - defstruct [{name, "No name"}, ] 2 + defstruct name "No name", nil 3 end user.ex structs2.exs Elixir defstruct nil user.ex 2 44

11 4.7 defstruct [{name, "No name"}, { , nil}] defstruct 4.7 struct $ elixir -e "u = %User{}; IO.inspect u. struct " User "User" struct User 4 Kernel.is_map/1 true true 45

12 4 $ elixir -e "u = %User{}; IO.inspect is_map(u)" Elixir Erlang Erlang Elixir struct struct struct3.exs ch04/struct3.exs 1 u = %{ struct User, name "foo", "foo@example.com"} 2 IO.inspect u Elixir %User{ "foo@example.com", name "foo"} struct3.exs ch04/struct3.exs 1 u = %{ struct User, name "foo", "foo@example.com"} 2 - IO.inspect u 2 + IO.inspect u[name] Elixir ** (UndefinedFunctionError) function User.fetch/2 is undefined (User does > not implement the Access behaviour) struct 46

13 4.7 Elixir http//elixir-lang.org/getting-started/structs.html bare maps Erlang Elixir bare struct4.exs ch04/struct4.exs 1 u = %User{name "foo", "foo@example.com"} 2 u = Map.merge(u, %{name "bar"}) 3 IO.inspect u Elixir %User{ "foo@example.com", name "bar"} struct4.exs ch04/struct4.exs 1 u = %User{name "foo", "foo@example.com"} 2 - u = Map.merge(u, %{name "bar"}) 2 + u = Map.merge(u, %User{name "bar"}) 3 IO.inspect u %User{ nil, name "bar"} nil %User{name "bar"} %{ struct User, name "bar", nil} u 47

14 4 struct4.exs ch04/struct4.exs 1 - u = %User{name "foo", "foo@example.com"} 1 + u = %{name "foo", "foo@example.com"} 2 u = Map.merge(u, %User{name "bar"}) 3 IO.inspect u %User{ nil, name "bar"} 1 u u %User{name "bar"} struct 2 3 u Map.merge/2 2 48

15 Phoenix HTML 15.1 ModestGreeter RAVT web/router.ex web/router.ex : 12 scope "/", ModestGreeter do 13 pipe_through :browser get "/", TopCont

15 Phoenix HTML 15.1 ModestGreeter RAVT web/router.ex web/router.ex : 12 scope "/", ModestGreeter do 13 pipe_through :browser 14 15 + get "/", TopController, :index 16 get "/hello/:name", HelloController,