switch import of mapping between python versions

Author: tomvanmele

CHANGELOG.md

@@ -496,6 +496,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 * Added `kwargs` to all child classes of `compas.data.Data`.
 * Added grasshopper component for drawing a frame.
 * Added `draw_origin` and `draw_axes`.
+* Added `compas.PY2`.
 
 ### Changed
 

src/compas/__init__.py

@@ -76,6 +76,9 @@
 Float formatting (``'<x>f'``) and integer formatting (``'d'``) specifiers are supported.
 """
 
+PY2 = compas._os.PY2
+"""bool: True if the current Python version is 2.x, False otherwise."""
+
 PY3 = compas._os.PY3
 """bool: True if the current Python version is 3.x, False otherwise."""
 

src/compas/_os.py

@@ -17,6 +17,7 @@
     class NotADirectoryError(Exception):
         pass
 
+PY2 = sys.version_info[0] == 2
 PY3 = sys.version_info[0] == 3
 SYMLINK_REGEX = re.compile(r"\n.*\<SYMLINKD\>\s(.*)\s\[(.*)\]\r")
 

src/compas/artists/colordict.py

@@ -1,5 +1,9 @@
+import compas
 from collections import defaultdict
-from collections import Mapping
+if compas.PY2:
+    from collections import Mapping
+else:
+    from collections.abc import Mapping
 from compas.colors import Color