Add linesegment module

The module defines a LineSegment class that displays a line segment in
two-dimensional coordinate system. It is defined by a start- and an
endpoint. It also contains a method to calculate the length.

linesegment.py

@@ -0,0 +1,33 @@
+#!/usr/bin/python3
+"""The linesegment module defines the class line_segment"""
+
+import point
+
+class LineSegment:
+    """The class LineSegment defines a two-dimensional line segment in the coordinate system
+    starting at a startpoint and ending at a endpoint."""
+    def __init__(self, startpoint=point.Point(), endpoint=point.Point()):
+        """Initialize the line segment."""
+        self.set_startpoint(startpoint)
+        self.set_endpoint(endpoint)
+    def set_startpoint(self, new_startpoint):
+        """Set or change the startpoint of the line segment. If not a Point object is given
+        the startpoint gets set to a default value of Point(0,0)"""
+        self.__startpoint = new_startpoint
+    def get_startpoint(self):
+        """Returns the current startpoint"""
+        return self.__startpoint
+    def set_endpoint(self, new_endpoint):
+        """Set or change the endpoint of the line segment. If not a Point object is given
+        the endpoint gets set to a default value of Point(0,0)"""
+        self.__endpoint = new_endpoint
+    def get_endpoint(self):
+        """Returns the current endpoint"""
+        return self.__endpoint
+    def get_length(self):
+        """Returns the length of the line segment."""
+        diff_x = abs(self.__startpoint.get_x() - self.__endpoint.get_x())
+        diff_y = abs(self.__startpoint.get_y() - self.__endpoint.get_y())
+        return ((diff_x ** 2) + (diff_y ** 2)) ** (1/2.0)
+    def draw(self):
+        """TODO: Draw the line segment in a canvas"""