From 1614e3b6b31116a27e117e87f1f34874a2896d3e Mon Sep 17 00:00:00 2001
From: Zach Daniel <zach@zachdaniel.dev>
Date: Tue, 29 Oct 2024 15:40:25 -0400
Subject: [PATCH] improvement: support `.unwrap!/2` on generated splode modules

---
 .../tutorials/get-started-with-splode.md      | 10 ++---
 lib/splode.ex                                 | 41 +++++++++++++++++++
 test/splode_test.exs                          | 16 ++++++++
 3 files changed, 61 insertions(+), 6 deletions(-)

diff --git a/documentation/tutorials/get-started-with-splode.md b/documentation/tutorials/get-started-with-splode.md
index d650996..2f1893f 100644
--- a/documentation/tutorials/get-started-with-splode.md
+++ b/documentation/tutorials/get-started-with-splode.md
@@ -147,15 +147,13 @@ end
 
 # Raising Exceptions
 
-To make a `!` version of a function that returns one of these errors is quite simple:
+To make a `!` version of a function, use `.unwrap!/2` on your splode module.
 
 ```elixir
 def get_user!(user_id) do
-  with {:ok, user} <- get_user(user_id) do
-    {:ok, user}
-  else
-    {:error, error} -> raise MyApp.Errors.to_class(error)
-  end
+  user_id
+  |> get_user()
+  |> MyApp.Errors.unwrap!()
 end
 
 def get_user(user_id) do
diff --git a/lib/splode.ex b/lib/splode.ex
index 6d65f8c..32e85da 100644
--- a/lib/splode.ex
+++ b/lib/splode.ex
@@ -97,6 +97,47 @@ defmodule Splode do
 
       @error_class_indices @error_classes |> Keyword.keys() |> Enum.with_index() |> Enum.into(%{})
 
+      @doc """
+      Raises an error if the result is an error, otherwise returns the result
+
+      Alternatively, you can use the `defsplode` macro, which does this automatically.
+
+      ### Options
+
+      - `:error_opts` - Options to pass to `to_error/2` when converting the returned error
+      - `:unknown_error_opts` - Options to pass to the unknown error if the function returns only `:error`.
+        not necessary if your function always returns `{:error, error}`.
+
+      ### Examples
+
+        def function(arg) do
+          case do_something(arg) do
+            :success -> :ok
+            {:success, result} -> {:ok, result}
+            {:error, error} -> {:error, error}
+          end
+        end
+
+        def function!!(arg) do
+          YourErrors.unwrap!(function(arg))
+        end
+      """
+      def unwrap!(result, opts \\ nil)
+      def unwrap!({:ok, result}, _opts), do: result
+      def unwrap!(:ok, _), do: :ok
+
+      def unwrap!({:error, error}, opts), do: raise(to_error(error, opts[:error_opts] || []))
+
+      def unwrap!(:error, opts),
+        do: raise(@error_classes[:unknown].exception(opts[:unknown_error_opts] || []))
+
+      def unwrap!(other, opts),
+        do:
+          raise(
+            ArgumentError,
+            "Invalid value provided to `splode!/2`:\n\n#{inspect(other)}"
+          )
+
       @impl true
       def set_path(errors, path) when is_list(errors) do
         Enum.map(errors, &set_path(&1, path))
diff --git a/test/splode_test.exs b/test/splode_test.exs
index 1eea7ae..33c7627 100644
--- a/test/splode_test.exs
+++ b/test/splode_test.exs
@@ -94,6 +94,22 @@ defmodule SplodeTest do
       merge_with: []
   end
 
+  defmodule Example do
+    def function() do
+      {:error, "Error"}
+    end
+
+    def function!() do
+      SystemError.unwrap!(function())
+    end
+  end
+
+  test "splode functions work" do
+    assert_raise SplodeTest.UnknownError, ~r/error: "Error"/, fn ->
+      Example.function!()
+    end
+  end
+
   test "splode_error?" do
     refute SystemError.splode_error?(:error)
     refute SystemError.splode_error?(%{})