Be able to set a default :base_dir option for use Tmp

README.md

@@ -24,6 +24,11 @@ Define your Tmp module:
 defmodule MyApp.Tmp do
   use Tmp
 end
+
+# Or with a custom base directory
+defmodule MyApp.CustomTmp do
+  use Tmp, base_dir: "/path/to/custom/base/dir"
+end
 ```
 
 Add it to your supervision tree:
@@ -50,7 +55,7 @@ end)
 When calling `MyApp.Tmp.dir/2`, you can pass the following options:
 
 - `:prefix` (optional) - Prefix for the temporary directory name, defaults to `nil`
-- `:base_dir` (optional) - Base directory for the temporary directory, defaults to `System.tmp_dir()`
+- `:base_dir` (optional) - Base directory for the temporary directory, defaults to `System.tmp_dir()` or the value set in `use Tmp`
 - `:timeout` (optional) - Timeout in milliseconds, defaults to `:infinity`
 
 ### Examples
@@ -67,6 +72,16 @@ end, prefix: "my_app", base_dir: "/tmp/custom_base")
 # => 4
 ```
 
+Using a custom base directory:
+
+```elixir
+MyApp.CustomTmp.dir(fn tmp_dir_path ->
+  # tmp_dir_path will be within "/path/to/custom/base/dir"
+  File.touch(Path.join(tmp_dir_path, "file_in_custom_dir"))
+  # ... other work
+end)
+```
+
 Error handling:
 
 ```elixir

lib/tmp.ex

@@ -10,6 +10,12 @@ defmodule Tmp do
         use Tmp
       end
 
+  Or with a custom base directory:
+
+      defmodule MyApp.CustomTmp do
+        use Tmp, base_dir: "/path/to/custom/base/dir"
+      end
+
   Add it to your supervision tree:
 
       children = [
@@ -24,12 +30,20 @@ defmodule Tmp do
         # then return a value
         {:ok, :foobar}
       end)
+
+  You can also override the base directory for a specific call:
+
+      MyApp.Tmp.dir(fn tmp_dir_path ->
+        # ...
+      end, base_dir: "/path/to/another/base/dir")
   """
 
-  defmacro __using__(_opts) do
+  defmacro __using__(opts) do
     quote do
       use Supervisor
 
+      @base_dir unquote(Keyword.get(opts, :base_dir))
+
       def start_link(opts) do
         Supervisor.start_link(__MODULE__, opts, name: opts[:name])
       end
@@ -44,6 +58,7 @@ defmodule Tmp do
       end
 
       def dir(function, options \\ []) when is_function(function, 1) do
+        options = Keyword.put_new(options, :base_dir, @base_dir)
         Tmp.dir(__MODULE__, function, options)
       end
     end
@@ -78,7 +93,7 @@ defmodule Tmp do
   """
   @spec dir(module(), function(), keyword()) :: term()
   def dir(module, function, options \\ []) when is_function(function, 1) do
-    base_dir = Keyword.get(options, :base_dir, System.tmp_dir())
+    base_dir = Keyword.get(options, :base_dir) || System.tmp_dir()
     prefix = Keyword.get(options, :prefix)
     timeout = Keyword.get(options, :timeout, :infinity)
     dirname = dirname(prefix)

test/tmp_test.exs

@@ -44,6 +44,9 @@ defmodule TmpTest do
                base_dir: base_dir,
                prefix: "test_base_dir"
              )
+
+    Process.sleep(100)
+    File.rmdir!(base_dir)
   end
 
   test "temporary directory exists in default base dir with correct prefix" do
@@ -153,4 +156,38 @@ defmodule TmpTest do
              )
            )
   end
+
+  test "uses base_dir option when provided" do
+    custom_base_dir = Path.join(System.tmp_dir(), "custom_base_dir")
+    File.mkdir_p!(custom_base_dir)
+
+    TestTmp.dir(
+      fn tmp_dir_path ->
+        assert String.starts_with?(tmp_dir_path, custom_base_dir)
+        assert File.exists?(tmp_dir_path)
+      end,
+      base_dir: custom_base_dir,
+      prefix: "test_custom_base_dir"
+    )
+  end
+
+  test "uses base_dir from use Tmp when set" do
+    defmodule CustomBaseDirTmp do
+      use Tmp, base_dir: Path.join(System.tmp_dir(), "custom_base_dir_module")
+    end
+
+    start_supervised!({CustomBaseDirTmp, name: CustomBaseDirTmp})
+
+    CustomBaseDirTmp.dir(
+      fn tmp_dir_path ->
+        assert String.starts_with?(
+                 tmp_dir_path,
+                 Path.join(System.tmp_dir(), "custom_base_dir_module")
+               )
+
+        assert File.exists?(tmp_dir_path)
+      end,
+      prefix: "test_custom_base_dir_module"
+    )
+  end
 end