From de957d3151094f89b7c289afa90080d6202199a5 Mon Sep 17 00:00:00 2001
From: sosokker <sirin_29@hotmail.co.th>
Date: Mon, 14 Aug 2023 23:20:48 +0700
Subject: [PATCH] add howto for self-referencing type hints

---
 self-referencing-hints.md | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)
 create mode 100644 self-referencing-hints.md

diff --git a/self-referencing-hints.md b/self-referencing-hints.md
new file mode 100644
index 0000000..1a50cda
--- /dev/null
+++ b/self-referencing-hints.md
@@ -0,0 +1,18 @@
+## Self-Referencing Type Hints
+
+Inside of a class, if you write a type hint that refers to the same class Python will raise an Error because the class is not known yet.   
+For example:
+```python
+class Money:
+    def __add__(self, other: Money) -> Money:  # ERROR: Money is unknown
+        """Return the sum of two money objects."""
+        ... (code omitted)
+```
+
+to fix this, add the following import:
+```python
+from __future__ import annotations
+
+class Money:
+    def __add__(self, other: Money) -> Money:  # OK!
+```
\ No newline at end of file