[Python-ideas] Pre-conditions and post-conditions

[Greg Ewing]

Wes Turner wrote:
>     I'm going to re-write that in a pseudo-Eiffel like syntax:

Maybe some magic could be done to make this work:

      def __init__(self, img: np.ndarray, x: int, y: int, width: int,
              height: int) -> None:

          def __require__():
              x >= 0
              y >= 0
              width >= 0
              height >= 0
              x + width <= pqry.opencv.width_of(img)
              y + height <= pqry.opencv.height_of(img)

          def __ensure__():
              (self.x, self.y) in self
              (self.x + self.width - 1, self.y + self.height - 1) in self
              (self.x + self.width, self.y + self.height) not in self

          # body of __init__ goes here...

-- 
Greg