Merge "Make 'FormattableColumn' comparable"

Author: Zuul

cliff/columns.py

@@ -26,6 +26,11 @@ def __eq__(self, other):
             self.__class__ == other.__class__ and self._value == other._value
         )
 
+    def __lt__(self, other):
+        return (
+            self.__class__ == other.__class__ and self._value < other._value
+        )
+
     @abc.abstractmethod
     def human_readable(self):
         """Return a basic human readable version of the data."""

cliff/tests/test_columns.py

@@ -33,3 +33,16 @@ def test_faux_column_human(self):
             u"I made this string myself: ['list', 'of', 'values']",
             c.human_readable(),
         )
+
+    def test_sorting(self):
+        cols = [
+            FauxColumn('foo'),
+            FauxColumn('bar'),
+            FauxColumn('baz'),
+            FauxColumn('foo'),
+        ]
+        cols.sort()
+        self.assertEqual(
+            ['bar', 'baz', 'foo', 'foo'],
+            [c.machine_readable() for c in cols],
+        )

releasenotes/notes/comparable-FormattableColumn-31c0030ced70b7fb.yaml

@@ -0,0 +1,9 @@
+---
+features:
+  - |
+    Instances of ``cliff.columns.FormattableColumn`` are now comparable. This
+    allows implementations of ``FormattableColumn`` storing primitive data
+    types or containers with primitive data types to be sorted using the
+    ``--sort-column`` option. Implementations of ``FormattableColumn`` that
+    store other types of data will still need to implement their own rich
+    comparison magic methods.