Add DS.getAxisByTag and refactor getAxis

Lib/fontTools/designspaceLib/__init__.py

@@ -2691,12 +2691,13 @@ class DesignSpaceDocument(LogMixin, AsDictMixin):
             names.append(axisDescriptor.name)
         return names
 
-    def getAxis(self, name):
+    def getAxis(self, name: str) -> AxisDescriptor | DiscreteAxisDescriptor | None:
         """Return the axis with the given ``name``, or ``None`` if no such axis exists."""
-        for axisDescriptor in self.axes:
-            if axisDescriptor.name == name:
-                return axisDescriptor
-        return None
+        return next((axis for axis in self.axes if axis.name == name), None)
+
+    def getAxisByTag(self, tag: str) -> AxisDescriptor | DiscreteAxisDescriptor | None:
+        """Return the axis with the given ``tag``, or ``None`` if no such axis exists."""
+        return next((axis for axis in self.axes if axis.tag == tag), None)
 
     def getLocationLabel(self, name: str) -> Optional[LocationLabelDescriptor]:
         """Return the top-level location label with the given ``name``, or

Tests/designspaceLib/designspace_test.py

@@ -1,6 +1,7 @@
 # coding=utf-8
 
 import os
+from pathlib import Path
 import re
 
 import pytest
@@ -21,6 +22,8 @@ from fontTools.designspaceLib import (
 from fontTools.designspaceLib.types import Range
 from fontTools.misc import plistlib
 
+from .fixtures import datadir
+
 
 def _axesAsDict(axes):
     """
@@ -1064,3 +1067,10 @@ def test_Range_post_init():
     assert r.minimum == -1
     assert r.maximum == 2
     assert r.default == -1
+
+
+def test_get_axes(datadir: Path) -> None:
+    ds = DesignSpaceDocument.fromfile(datadir / "test_v5.designspace")
+
+    assert ds.getAxis("Width") is ds.getAxisByTag("wdth")
+    assert ds.getAxis("Italic") is ds.getAxisByTag("ital")