No more binding with a list

Author: José Valim

lib/elixir/lib/kernel.ex

@@ -2054,8 +2054,9 @@ defmodule Kernel do
   defp typespec(_),         do: false
 
   @doc """
-  Returns the binding as a keyword list where the variable name
-  is the key and the variable value is the value.
+  Returns the binding for the given context as a keyword list.
+
+  The variable name is the key and the variable value is the value.
 
   ## Examples
 
@@ -2066,59 +2067,18 @@ defmodule Kernel do
       iex> binding()
       [x: 2]
 
-  """
-  defmacro binding() do
-    do_binding(nil, nil, __CALLER__.vars, Macro.Env.in_match?(__CALLER__))
-  end
-
-  @doc """
-  Receives a list of atoms at compilation time and returns the
-  binding of the given variables as a keyword list where the
-  variable name is the key and the variable value is the value.
-
-  In case a variable in the list does not exist in the binding,
-  it is not included in the returned result.
-
-  ## Examples
-
-      iex> x = 1
-      iex> binding([:x, :y])
-      [x: 1]
-
-  """
-  defmacro binding(list) when is_list(list) do
-    do_binding(list, nil, __CALLER__.vars, Macro.Env.in_match?(__CALLER__))
-  end
-
-  defmacro binding(context) when is_atom(context) do
-    do_binding(nil, context, __CALLER__.vars, Macro.Env.in_match?(__CALLER__))
-  end
-
-  @doc """
-  Receives a list of atoms at compilation time and returns the
-  binding of the given variables in the given context as a keyword
-  list where the variable name is the key and the variable value
-  is the value.
-
-  In case a variable in the list does not exist in the binding,
-  it is not included in the returned result.
-
-  ## Examples
-
-      iex> var!(x, :foo) = 1
-      iex> binding([:x, :y])
+      iex> binding(:foo)
       []
-      iex> binding([:x, :y], :foo)
+      iex> var!(x, :foo) = 1
+      1
+      iex> binding(:foo)
       [x: 1]
 
   """
-  defmacro binding(list, context) when is_list(list) and is_atom(context) do
-    do_binding(list, context, __CALLER__.vars, Macro.Env.in_match?(__CALLER__))
-  end
-
-  defp do_binding(list, context, vars, in_match) do
-    for {v, c} <- vars, c == context, list == nil or :lists.member(v, list) do
-      {v, wrap_binding(in_match, {v, [], c})}
+  defmacro binding(context \\ nil) do
+    in_match? = Macro.Env.in_match?(__CALLER__)
+    for {v, c} <- __CALLER__.vars, c == context do
+      {v, wrap_binding(in_match?, {v, [], c})}
     end
   end
 

lib/elixir/test/elixir/kernel_test.exs

@@ -31,14 +31,14 @@ defmodule KernelTest do
 
   test "match?/2" do
     assert match?(_, List.first(1)) == true
-    assert binding([:x]) == []
+    assert binding() == []
 
     a = List.first([0])
     assert match?(b when b > a, 1) == true
-    assert binding([:b]) == []
+    assert binding() == [a: 0]
 
     assert match?(b when b > a, -1) == false
-    assert binding([:b]) == []
+    assert binding() == [a: 0]
   end
 
   test "nil?/1" do
@@ -134,21 +134,19 @@ defmodule KernelTest do
     assert apply(fn x -> x * 2 end, [2]) == 4
   end
 
-  test "binding/0, binding/1 and binding/2" do
+  test "binding/0 and binding/1" do
     x = 1
-    assert binding == [x: 1]
-    assert binding([:x, :y]) == [x: 1]
-    assert binding([:x, :y], nil) == [x: 1]
+    assert binding() == [x: 1]
 
     x = 2
-    assert binding == [x: 2]
+    assert binding() == [x: 2]
 
     y = 3
-    assert binding == [x: 2, y: 3]
+    assert binding() == [x: 2, y: 3]
 
-    var!(x, :foo) = 2
-    assert binding(:foo) == [x: 2]
-    assert binding([:x, :y], :foo) == [x: 2]
+    var!(x, :foo) = 4
+    assert binding() == [x: 2, y: 3]
+    assert binding(:foo) == [x: 4]
   end
 
   defmodule User do