From f120be17e4b1d63bd98c2390cf4ec39b8e61e8fd Mon Sep 17 00:00:00 2001
From: Cosimo Lupo <clupo@google.com>
Date: Tue, 5 May 2020 18:15:51 +0100
Subject: [PATCH] ufoLib/utils: define _VersionTupleEnumMixin class

---
 Lib/fontTools/ufoLib/utils.py | 33 +++++++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)

diff --git a/Lib/fontTools/ufoLib/utils.py b/Lib/fontTools/ufoLib/utils.py
index effc71fdf..85878b47a 100644
--- a/Lib/fontTools/ufoLib/utils.py
+++ b/Lib/fontTools/ufoLib/utils.py
@@ -36,6 +36,39 @@ def deprecated(msg=""):
     return deprecated_decorator
 
 
+# To be mixed with enum.Enum in UFOFormatVersion and GLIFFormatVersion
+class _VersionTupleEnumMixin:
+    @property
+    def major(self):
+        return self.value[0]
+
+    @property
+    def minor(self):
+        return self.value[1]
+
+    @classmethod
+    def _missing_(cls, value):
+        # allow to initialize a version enum from a single (major) integer
+        if isinstance(value, int):
+            return cls((value, 0))
+        # or from None to obtain the current default version
+        if value is None:
+            return cls.default()
+        return super()._missing_(value)
+
+    def __str__(self):
+        return f"{self.major}.{self.minor}"
+
+    @classmethod
+    def default(cls):
+        # get the latest defined version (i.e. the max of all versions)
+        return max(cls.__members__.values())
+
+    @classmethod
+    def supported_versions(cls):
+        return frozenset(cls.__members__.values())
+
+
 if __name__ == "__main__":
     import doctest