fix #1112: do not modify input list when assigning points

CHANGELOG.md

@@ -18,6 +18,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 * Updated workflows to v2.
 * Changed deepcopy of `RhinoBrep` to use the native `Rhino.Geometry` mechanism.
 * The normal of the cutting plane is no longer flipped in `compas_rhino.geometry.RhinoBrep`.
+* Fixed `Polygon` constructor to not modify the input list of points.
 
 ### Removed
 

src/compas/geometry/primitives/polygon.py

@@ -132,7 +132,7 @@ def points(self):
     @points.setter
     def points(self, points):
         if points[-1] == points[0]:
-            del points[-1]
+            points = points[:-1]
         self._points = [Point(*xyz) for xyz in points]
         self._lines = None
 

tests/compas/geometry/test_polygon.py

@@ -25,6 +25,14 @@ def test_polygon():
     assert polygon.lines == [(a, b) for a, b in pairwise(points + points[:1])]
 
 
+def test_ctor_does_not_modify_input_params():
+    pts = [[0, 0, 0], [1, 0, 0], [1, 1, 0], [0, 1, 0], [0, 0, 0]]
+
+    polygon = Polygon(pts)
+    assert len(pts) == 5
+    assert len(polygon.points) == 4, "The last point (matching the first) should have been removed"
+
+
 def test_equality():
     points1 = [[0, 0, x] for x in range(5)]
     polygon1 = Polygon(points1)