Promote @impl true in behaviour examples

Signed-off-by: José Valim <jose.valim@plataformatec.com.br>

Author: José Valim

lib/elixir/lib/dynamic_supervisor.ex

@@ -51,6 +51,7 @@ defmodule DynamicSupervisor do
           DynamicSupervisor.start_link(__MODULE__, arg, name: __MODULE__)
         end
 
+        @impl true
         def init(_arg) do
           DynamicSupervisor.init(strategy: :one_for_one)
         end
@@ -84,6 +85,7 @@ defmodule DynamicSupervisor do
           Supervisor.start_child(__MODULE__, [foo, bar, baz])
         end
 
+        @impl true
         def init(initial_arg) do
           children = [
             # Or the deprecated: worker(MyWorker, [initial_arg])
@@ -110,6 +112,7 @@ defmodule DynamicSupervisor do
           DynamicSupervisor.start_child(__MODULE__, spec)
         end
 
+        @impl true
         def init(initial_arg) do
           DynamicSupervisor.init(
             strategy: :one_for_one,
@@ -208,9 +211,6 @@ defmodule DynamicSupervisor do
       end
 
       defoverridable child_spec: 1
-
-      @doc false
-      def init(arg)
     end
   end
 

lib/elixir/lib/gen_server.ex

@@ -23,10 +23,17 @@ defmodule GenServer do
 
         # Callbacks
 
+        @impl true
+        def init(stack) do
+          {:ok, stack}
+        end
+
+        @impl true
         def handle_call(:pop, _from, [h | t]) do
           {:reply, h, t}
         end
 
+        @impl true
         def handle_cast({:push, item}, state) do
           {:noreply, [item | state]}
         end
@@ -151,22 +158,15 @@ defmodule GenServer do
 
         # Server (callbacks)
 
+        @impl true
         def handle_call(:pop, _from, [h | t]) do
           {:reply, h, t}
         end
 
-        def handle_call(request, from, state) do
-          # Call the default implementation from GenServer
-          super(request, from, state)
-        end
-
+        @impl true
         def handle_cast({:push, item}, state) do
           {:noreply, [item | state]}
         end
-
-        def handle_cast(request, state) do
-          super(request, state)
-        end
       end
 
   In practice, it is common to have both server and client functions in
@@ -196,11 +196,13 @@ defmodule GenServer do
           GenServer.start_link(__MODULE__, %{})
         end
 
+        @impl true
         def init(state) do
           schedule_work() # Schedule work to be performed on start
           {:ok, state}
         end
 
+        @impl true
         def handle_info(:work, state) do
           # Do the desired work here
           schedule_work() # Reschedule once more
@@ -664,8 +666,8 @@ defmodule GenServer do
             {:ok, args}
           end
 
-      But you want to define your own implementation that converts the \
-      arguments given to GenServer.start_link/3 to the server state
+      You can copy the implementation above or define your own that converts \
+      the arguments given to GenServer.start_link/3 to the server state.
       """
 
       :elixir_errors.warn(env.line, env.file, message)

lib/elixir/lib/supervisor.ex

@@ -28,14 +28,17 @@ defmodule Supervisor do
 
         ## Callbacks
 
+        @impl true
         def init(stack) do
           {:ok, stack}
         end
 
+        @impl true
         def handle_call(:pop, _from, [h | t]) do
           {:reply, h, t}
         end
 
+        @impl true
         def handle_cast({:push, h}, t) do
           {:noreply, [h | t]}
         end
@@ -342,6 +345,7 @@ defmodule Supervisor do
           Supervisor.start_link(__MODULE__, arg, name: __MODULE__)
         end
 
+        @impl true
         def init(_arg) do
           children = [
             {Stack, [:hello]}
@@ -476,9 +480,6 @@ defmodule Supervisor do
       end
 
       defoverridable child_spec: 1
-
-      @doc false
-      def init(arg)
     end
   end