Merge pull request #45 from tverlaan/tv_better_try_wrapper

Support `catch` as part of `do`-block
arjan · Feb 12, 2021 · becb785 · becb785
2 parents 557f1fa c628978
commit becb785
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Showing 3 changed files with 105 additions and 46 deletions.
diff --git a/lib/decorator/decorate.ex b/lib/decorator/decorate.ex
@@ -158,15 158,11 @@ defmodule Decorator.Decorate do
  defp ensure_do([{:do, _} | _] = body), do: body
  defp ensure_do(body), do: [do: body]
 
- defp apply_decorator(context, mfa, do: body) do
- [do: apply_decorator(context, mfa, body)]
- end
-
- defp apply_decorator(context, mfa, do: body, rescue: rescue_block) do
- [
- do: apply_decorator(context, mfa, body),
- rescue: apply_decorator_to_rescue(context, mfa, rescue_block)
- ]
  # a do-block will automatically be put in a `try do` by Elixir when one of the keywords
  # `rescue`, `catch` or `after` is present. hence `try_clauses`.
  defp apply_decorator(context, mfa, [{:do, body} | try_clauses]) do
  [do: apply_decorator(context, mfa, body)]  
  apply_decorator_try_clauses(context, mfa, try_clauses)
  end
 
  defp apply_decorator(context, {module, fun, args}, body) do
@@ -181,8 177,21 @@ defmodule Decorator.Decorate do
  raise ArgumentError, "Invalid decorator: #{inspect(decorator)}"
  end
 
- defp apply_decorator_to_rescue(context, mfa, rescue_block) do
- rescue_block
  defp apply_decorator_try_clauses(_, _, []), do: []
 
  defp apply_decorator_try_clauses(context, mfa, [{:after, after_block} | try_clauses]) do
  [after: apply_decorator(context, mfa, after_block)]  
  apply_decorator_try_clauses(context, mfa, try_clauses)
  end
 
  defp apply_decorator_try_clauses(context, mfa, [{try_clause, try_match_block} | try_clauses])
  when try_clause in [:rescue, :catch] do
  [{try_clause, apply_decorator_to_try_clause_block(context, mfa, try_match_block)}]  
  apply_decorator_try_clauses(context, mfa, try_clauses)
  end
 
  defp apply_decorator_to_try_clause_block(context, mfa, try_match_block) do
  try_match_block
  |> Enum.map(fn {:->, meta, [match, body]} ->
  {:->, meta, [match, apply_decorator(context, mfa, body)]}
  end)

diff --git a/test/exception_test.exs b/test/exception_test.exs
diff --git a/test/try_wrapper_test.exs b/test/try_wrapper_test.exs
@@ -0,0 1,85 @@
 # two arguments
 defmodule DecoratorTest.Fixture.TryWrapperDecorator do
  use Decorator.Define, test: 0
 
  def test(body, _context) do
  {:ok, body}
  end
 end
 
 defmodule DecoratorTest.Fixture.TryWrapperTestModule do
  use DecoratorTest.Fixture.TryWrapperDecorator
 
  @decorate test()
  def rescued(a) do
  if a == :raise do
  raise RuntimeError, "text"
  end
 
  a
  rescue
  _ in RuntimeError -> :error
  end
 
  @decorate test()
  def catched(a) do
  if a == :throw do
  throw(a)
  end
 
  a
  catch
  _ -> :thrown
  end
 
  @decorate test()
  def try_after(a) do
  a
  after
  IO.write("after")
  end
 
  @decorate test()
  def rescued_and_catched(a) do
  case a do
  :throw -> throw(a)
  :raise -> raise RuntimeError, "text"
  a -> a
  end
  rescue
  _ in RuntimeError -> :error
  catch
  _ -> :thrown
  end
 end
 
 defmodule DecoratorTest.TryWrapper do
  use ExUnit.Case
  import ExUnit.CaptureIO
 
  alias DecoratorTest.Fixture.TryWrapperTestModule
 
  test "Functions which have a 'rescue' clause" do
  assert {:ok, 3} = TryWrapperTestModule.rescued(3)
  assert {:ok, :error} = TryWrapperTestModule.rescued(:raise)
  end
 
  test "Functions which have a 'catch' clause" do
  assert {:ok, 3} = TryWrapperTestModule.catched(3)
  assert {:ok, :thrown} = TryWrapperTestModule.catched(:throw)
  end
 
  test "Functions which have an 'after' clause" do
  assert capture_io(fn ->
  send(self(), TryWrapperTestModule.try_after(3))
  end) == "after"
 
  assert_received {:ok, 3}
  end
 
  test "Functions which have a 'rescue' and a 'catch' clause" do
  assert {:ok, 3} = TryWrapperTestModule.rescued_and_catched(3)
  assert {:ok, :thrown} = TryWrapperTestModule.rescued_and_catched(:throw)
  assert {:ok, :error} = TryWrapperTestModule.rescued_and_catched(:raise)
  end
 end