math.vector3 has 100% test coverage. Remove __cmp__ method (not used)…

…. Improve docs.

lena/math/vector3.py

@@ -40,9 +40,10 @@
 if that makes sense for the operations used
 (types are not tested during the initialization).
 For example, vectors in the examples above have integer coordinates,
-which can change if we multiply them by floats
-or rotate. For usual vector additions, though, their coordinates
-remain integer.
+which will become floats if we multiply them by floats,
+divide or maybe rotate.
+For usual vector additions or subtractions, though,
+their coordinates will remain integer.
 """
 
 from math import sin, cos, acos, pi, atan2, sqrt
@@ -311,6 +312,8 @@ def _mag2(self):
         """
         return self.dot(self)
 
+    # todo: probably make r2 an attribute (like rho2)
+    # and why do we have a separate method _mag2?
     def getr2(self):
         return self._mag2()
 
@@ -346,12 +349,13 @@ def __ne__(self, B):
 
     ## Prohibit comparison methods <, <=, >, >=, __cmp__
 
-    def __cmp__(self, B):
-        # works fine for Python 2, but __lt__, etc.
-        # should be also implemented for Python 3.
-        raise lena.core.LenaTypeError(
-            "comparison is not supported for vector3"
-        )
+    # this method is never called. Probably remove.
+    # def __cmp__(self, B):
+    #     # works fine for Python 2, but __lt__, etc.
+    #     # should be also implemented for Python 3.
+    #     raise lena.core.LenaTypeError(
+    #         "comparison is not supported for vector3"
+    #     )
 
     def __lt__(self, B):
         raise lena.core.LenaTypeError(
@@ -378,8 +382,8 @@ def __ge__(self, B):
     def __getitem__(self, i):
         return self._v[i]
 
-    def __setitem__(self, key, value):
-        self._v[key] = float(value)
+    def __setitem__(self, ind, value):
+        self._v[ind] = float(value)
 
     def __iter__(self):
         return iter(self._v)
@@ -412,6 +416,8 @@ def isclose(self, B, rel_tol=1e-09, abs_tol=0.0):
     # http://blog.teamtreehouse.com/operator-overloading-python
 
     def __nonzero__(self):
+        # implement truth value testing and bool()
+        # not used in Python 3 tests
         return self._mag2() != 0
 
     ## Regular Binary Operations
@@ -433,6 +439,10 @@ def __div__(self, c):
         >>> v1 / 2
         vector3(0.0, 0.5, 1.0)
         """
+        # in Python 3 4/2 = 2.,
+        # while in Python 2 4/2 is integer 2!
+        # so there is no need to care about preserving integers:
+        # they will be lost in general.
         return 1./c * self
 
     def __truediv__(self, c):

tests/math/test_vector3.py

@@ -1,5 +1,6 @@
 import pytest
 
+import lena.core
 from lena.math import vector3
 from lena.core.exceptions import LenaTypeError
 
@@ -36,6 +37,46 @@ def test_operations():
     v1 /= 2
     assert v1 == vector3(3, 4, 5)
 
+    # after division vector representation will be with floats
+    assert str(v1) == "vector3(3.0, 4.0, 5.0)"
+
+    # test all assignments / getters
+    v2 = vector3(0, 0, 0)
+    v2.x = 1
+    v2.y = 2
+    v2.z = 3
+    assert v2 == vector3(1, 2, 3)
+
+    # r2 getter works
+    assert v2.getr2() == 14
+
+    # != works
+    assert v1 != v2
+
+    # != with a wrong type raises
+    with pytest.raises(lena.core.LenaTypeError):
+        v1 != 0
+
+    # comparison with a wrong type raises
+    with pytest.raises(lena.core.LenaTypeError):
+        v1 < 0
+
+    # iter works
+    assert list(coord for coord in v2) == [1, 2, 3]
+
+    # container length is 3
+    assert len(v1) == 3
+
+    # we also have this method!
+    v2[2] = 4
+    assert v2 == vector3(1, 2, 4)
+
+    # we can add a list to vector3! From the right side.
+    assert [1.1, 2.2, 3.3] + v2 == vector3(2.1, 4.2, 7.3)
+
+    # non-zero works
+    assert bool(v2)
+
 
 def test_cylindrical():
     v1 = vector3(3, 4, 5)