Use Mix.Shell.printable_app_name

Author: José Valim

lib/mix/lib/mix/project_stack.ex

@@ -61,18 +61,18 @@ defmodule Mix.ProjectStack do
     end
   end
 
-  @spec print_app?() :: boolean
-  def print_app? do
+  @spec printable_app_name() :: atom | nil
+  def printable_app_name do
     get_and_update fn %{stack: stack} = state ->
       case stack do
         [] ->
-          {false, state}
+          {nil, state}
         [%{io_done: true}|_] ->
-          {false, state}
+          {nil, state}
         [h|t] ->
           h = %{h | io_done: true}
           t = Enum.map(t, &%{&1 | io_done: false})
-          {has_app?(h), %{state | stack: [h|t]}}
+          {h.config[:app], %{state | stack: [h|t]}}
       end
     end
   end
@@ -150,10 +150,6 @@ defmodule Mix.ProjectStack do
     Map.take(h, [:name, :config, :file, :pos])
   end
 
-  defp has_app?(%{config: config}) do
-    config[:app]
-  end
-
   defp get_and_update(fun) do
     Agent.get_and_update __MODULE__, fun, @timeout
   end

lib/mix/lib/mix/shell.ex

@@ -48,13 +48,18 @@ defmodule Mix.Shell do
   defcallback print_app() :: any
 
   @doc """
-  Returns if we should print application name to shell.
+  Returns the printable app name.
+
+  This function returns the current application name
+  but only if the application name should be printed.
 
   Calling this function automatically toggles its value
-  to false.
+  to false until the current project is re-entered. The
+  goal is to exactly avoid printing the application name
+  multiple times.
   """
-  def print_app? do
-    Mix.ProjectStack.print_app?
+  def printable_app_name do
+    Mix.ProjectStack.printable_app_name
   end
 
   @doc """

lib/mix/lib/mix/shell/io.ex

@@ -12,8 +12,8 @@ defmodule Mix.Shell.IO do
   was not printed yet.
   """
   def print_app do
-    if Mix.Shell.print_app? do
-      IO.puts "==> #{Mix.Project.config[:app]}"
+    if name = Mix.Shell.printable_app_name do
+      IO.puts "==> #{name}"
     end
   end
 

lib/mix/lib/mix/shell/process.ex

@@ -44,8 +44,8 @@ defmodule Mix.Shell.Process do
   was not printed yet.
   """
   def print_app do
-    if Mix.Shell.print_app? do
-      send self, {:mix_shell, :info, ["==> #{Mix.Project.config[:app]}"]}
+    if name = Mix.Shell.printable_app_name do
+      send self, {:mix_shell, :info, ["==> #{name}"]}
     end
   end