Feature/7 interval initialization

intervals/__init__.py

@@ -72,8 +72,24 @@ def wrapper(self, arg):
     return wrapper
 
 
+class ClosedInterval(type):
+    """
+    Supports initialization of intervals using square brackets and makes them
+    closed intervals.
+
+    eg.
+
+    IntInterval[1, 4] == IntInterval([1, 4])
+    """
+    def __getitem__(self, bounds):
+        lower_inc = upper_inc = True
+        return self(bounds, lower_inc, upper_inc)
+
+
 @total_ordering
 class AbstractInterval(object):
+    __metaclass__ = ClosedInterval
+
     step = None
     type = None
     parser = IntervalParser()
@@ -151,6 +167,20 @@ def __init__(
             30
 
         """
+
+        # This if-block adds support for parentheses as open intervals.
+        # Note: If the interval is initialized with the parentheses with two
+        #       objects of same type, eg.
+        #       IntInterval(1, 4)
+        #       the bounds and lower_inc are received of that type and
+        #       upper_inc is None.
+        #
+        # eg.
+        # IntInterval(1, 4) == IntInterval((1, 4))
+        if type(bounds) == type(lower_inc) and not upper_inc:
+            bounds = (bounds, lower_inc)
+            lower_inc = upper_inc = None
+
         self.lower, self.upper, self.lower_inc, self.upper_inc = (
             self.parser(bounds, lower_inc, upper_inc)
         )

tests/test_initialization.py

@@ -88,6 +88,12 @@ def test_supports_integers(self):
         assert interval.lower_inc
         assert interval.upper_inc
 
+    def test_uses_two_numbers_with_parentheses_as_open_interval(self):
+        assert IntInterval(1, 2) == IntInterval((1, 2))
+
+    def test_uses_two_numbers_with_square_brackets_as_closed_interval(self):
+        assert IntInterval[1, 2] == IntInterval([1, 2])
+
     @mark.parametrize('number_range',
         (
             (3, 2),