Add iex option to automatically purge recompiled modules (#13919)

Author: jonatanklosko

lib/iex/lib/iex.ex

@@ -357,7 +357,7 @@ defmodule IEx do
       13
 
   It is possible to load another file by configuring the `iex` application's `dot_iex`
-  value (`config :iex, dot_iex: "PATH"` or `IEx.Config.configure(dot_iex: "PATH")`)
+  value (`config :iex, dot_iex: "PATH"` or `IEx.configure(dot_iex: "PATH")`)
   or supplying the `--dot-iex` option to IEx. See `iex --help`.
 
   In case of remote nodes, the location of the `.iex.exs` files are taken
@@ -488,6 +488,9 @@ defmodule IEx do
     * `:alive_continuation_prompt` - used when `Node.alive?/0` returns
       `true` and more input is expected
 
+    * `:auto_reload` - when set to `true`, automatically purges in-memory
+      modules when they get invalidated by a concurrent compilation
+
   The following values in the prompt string will be replaced appropriately:
 
     * `%counter` - the index of the history

lib/iex/lib/iex/config.ex

@@ -14,7 +14,8 @@ defmodule IEx.Config do
     :alive_continuation_prompt,
     :width,
     :parser,
-    :dot_iex
+    :dot_iex,
+    :auto_reload
   ]
 
   # Read API
@@ -93,6 +94,10 @@ defmodule IEx.Config do
     Application.get_env(:iex, :dot_iex)
   end
 
+  def auto_reload?() do
+    Application.fetch_env!(:iex, :auto_reload)
+  end
+
   # Used by default on evaluation cycle
   defp default_color(:eval_interrupt), do: [:yellow]
   defp default_color(:eval_result), do: [:yellow]
@@ -199,6 +204,7 @@ defmodule IEx.Config do
   defp validate_option({:width, new}) when is_integer(new), do: :ok
   defp validate_option({:parser, tuple}) when tuple_size(tuple) == 3, do: :ok
   defp validate_option({:dot_iex, path}) when is_binary(path), do: :ok
+  defp validate_option({:auto_reload, enabled}) when is_boolean(enabled), do: :ok
 
   defp validate_option(option) do
     raise ArgumentError, "invalid configuration #{inspect(option)}"

lib/iex/lib/iex/mix_listener.ex

@@ -25,13 +25,8 @@ defmodule IEx.MixListener do
 
   @impl true
   def handle_call(:purge, _from, state) do
-    for module <- state.to_purge do
-      :code.purge(module)
-      :code.delete(module)
-    end
-
+    purge_modules(state.to_purge)
     status = if Enum.empty?(state.to_purge), do: :noop, else: :ok
-
     {:reply, status, %{state | to_purge: MapSet.new()}}
   end
 
@@ -43,13 +38,27 @@ defmodule IEx.MixListener do
       {:noreply, state}
     else
       %{changed: changed, removed: removed} = info.modules_diff
-      state = update_in(state.to_purge, &Enum.into(changed, &1))
-      state = update_in(state.to_purge, &Enum.into(removed, &1))
-      {:noreply, state}
+
+      if IEx.Config.auto_reload?() do
+        purge_modules(changed)
+        purge_modules(removed)
+        {:noreply, state}
+      else
+        state = update_in(state.to_purge, &Enum.into(changed, &1))
+        state = update_in(state.to_purge, &Enum.into(removed, &1))
+        {:noreply, state}
+      end
     end
   end
 
   def handle_info(_message, state) do
     {:noreply, state}
   end
+
+  defp purge_modules(modules) do
+    for module <- modules do
+      :code.purge(module)
+      :code.delete(module)
+    end
+  end
 end

lib/iex/mix.exs

@@ -18,7 +18,8 @@ defmodule IEx.MixProject do
         inspect: [pretty: true],
         history_size: 20,
         default_prompt: "%prefix(%counter)>",
-        alive_prompt: "%prefix(%node)%counter>"
+        alive_prompt: "%prefix(%node)%counter>",
+        auto_reload: false
       ]
     ]
   end