FIX: API compatib th sympy for Interval objects

Author: richardotis

symengine/lib/symengine_wrapper.pyx

@@ -2999,8 +2999,23 @@ cdef class Set(Expr):
 
 class Interval(Set):
 
-    def __new__(self, *args):
-        return interval(*args)
+    def __new__(self, *args, left_open=None, right_open=None):
+        list_args = list(args)
+        if ((left_open is not None) and (right_open is None)) or ((left_open is None) and (right_open is not None)):
+            raise ValueError("Both (or neither) keyword arguments for Interval should be specified")
+        if left_open is not None:
+            list_args.append(left_open)
+        if right_open is not None:
+            list_args.append(right_open)
+        return interval(*list_args)
+
+    @property
+    def start(self):
+        return self.args[0]
+
+    @property
+    def end(self):
+        return self.args[1]
 
     def _sympy_(self):
         import sympy

symengine/tests/test_sets.py

@@ -6,7 +6,9 @@
 
 def test_Interval():
     assert Interval(0, oo) == Interval(0, oo, False, True)
+    assert Interval(0, oo) == Interval(0, oo, left_open=False, right_open=True)
     assert Interval(-oo, 0) == Interval(-oo, 0, True, False)
+    assert Interval(-oo, 0) == Interval(-oo, 0, left_open=True, right_open=False)
     assert Interval(oo, -oo) == EmptySet()
     assert Interval(oo, oo) == EmptySet()
     assert Interval(-oo, -oo) == EmptySet()
@@ -18,6 +20,9 @@ def test_Interval():
     assert Interval(1, 1, True, True) == EmptySet()
     assert Interval(1, 2).union(Interval(2, 3)) == Interval(1, 3)
 
+    assert Interval(-oo, 0).start == -oo
+    assert Interval(-oo, 0).end == 0
+
 
 def test_EmptySet():
     E = EmptySet()