Allow __FILE__ and __LINE__ customization in EDITOR

Author: José Valim

lib/iex/lib/iex/helpers.ex

@@ -222,20 +222,33 @@ defmodule IEx.Helpers do
   end
 
   @doc """
-  Opens the given module, module/function/arity or file.
+  Opens the given module, module/function/arity or `{file, line}`.
 
   This function uses the `ELIXIR_EDITOR` environment variable
-  and falls back to EDITOR if the former is not available.
+  and falls back to `EDITOR` if the former is not available.
 
-  Since this function prints the result returned by the
-  editor, `ELIXIR_EDITOR` can be set "echo" if you prefer
-  to display the location rather than opening it.
+  By default, it attempts to open the file and line using the
+  `file:line` notation. For example, if your editor is called
+  `subl`, it will open the file as:
+
+      subl path/to/file:line
+
+  Custom editors are supported by using the __FILE__ and __LINE__
+  notations. For example, vi/vim users can set `ELIXIR_EDITOR` to:
+
+      ELIXIR_EDITOR="vi +__LINE__ __FILE__"
+
+  and Elixir will properly interpolate values.
+
+  Since this function prints the result returned by the editor,
+  `ELIXIR_EDITOR` can be set "echo" if you prefer to display the
+  location rather than opening it.
 
   ## Examples
 
       iex> open MyApp
       iex> open MyApp.fun/2
-      iex> open "path/to/file"
+      iex> open {"path/to/file", 1}
 
   """
   defmacro open(term) do

lib/iex/lib/iex/introspection.ex

@@ -84,22 +84,25 @@ defmodule IEx.Introspection do
   end
 
   def open({file, line}) when is_binary(file) and is_integer(line) do
-    if File.regular?(file) do
-      open("#{file}:#{line}")
-    else
-      puts_error("Could not open: #{inspect file}. File is not available.")
+    cond do
+      not File.regular?(file) ->
+        puts_error("Could not open: #{inspect file}. File is not available.")
+      editor = System.get_env("ELIXIR_EDITOR") || System.get_env("EDITOR") ->
+        command =
+          if editor =~ "__FILE__" or editor =~ "__LINE__" do
+            editor
+            |> String.replace("__FILE__", inspect(file))
+            |> String.replace("__LINE__", Integer.to_string(line))
+          else
+            "#{editor} #{inspect file}:#{line}"
+          end
+        IO.write IEx.color(:eval_info, :os.cmd(String.to_charlist(command)))
+      true ->
+        puts_error("Could not open: #{inspect file}. " <>
+                   "Please set the ELIXIR_EDITOR or EDITOR environment variables with the " <>
+                   "command line invocation of your favorite EDITOR.")
     end
-    dont_display_result()
-  end
 
-  def open(path) when is_binary(path) do
-    if editor = System.get_env("ELIXIR_EDITOR") || System.get_env("EDITOR") do
-      IO.write IEx.color(:eval_info, :os.cmd('#{editor} #{inspect path}'))
-    else
-      puts_error("Could not open: #{inspect path}. " <>
-                 "Please set the ELIXIR_EDITOR or EDITOR environment variables with the " <>
-                 "command line invocation of your favorite EDITOR.")
-    end
     dont_display_result()
   end
 

lib/iex/test/iex/helpers_test.exs

@@ -125,6 +125,15 @@ defmodule IEx.HelpersTest do
   describe "open" do
     @iex_helpers Path.expand("../../lib/iex/helpers.ex", __DIR__)
     @elixir_erl Path.expand("../../../elixir/src/elixir.erl", __DIR__)
+    @editor System.get_env("ELIXIR_EDITOR")
+
+    test "opens __FILE__ and __LINE__" do
+      System.put_env("ELIXIR_EDITOR", "echo __LINE__:__FILE__")
+      assert capture_iex("open({#{inspect __ENV__.file}, 3})") |> maybe_trim_quotes() ==
+             "3:#{__ENV__.file}"
+    after
+      System.put_env("ELIXIR_EDITOR", @editor)
+    end
 
     test "opens Elixir module" do
       assert capture_iex("open(IEx.Helpers)") |> maybe_trim_quotes() =~
@@ -210,11 +219,6 @@ defmodule IEx.HelpersTest do
              "Could not open: \"foo\". File is not available."
     end
 
-    test "opens given path" do
-      assert capture_iex("open(#{inspect __ENV__.file})") |> maybe_trim_quotes() ==
-             __ENV__.file
-    end
-
     defp maybe_trim_quotes(string) do
       case :os.type do
         {:win32, _} -> String.trim(string, "\"")