[Tutor] line class

[Alan Gauld]

"Christopher Spears" <cspears2002 at yahoo.com> wrote


> class Point(object):
>    def __init__(self, x=0.0,y=0.0):
>        self.x = float(x)
> self.y = float(y)
> 
>    def __repr__(self):
>        coord = (self.x,self.y)
> return coord

You could add a couple of methods here to get deltaX and 
deltaY values Or even define __sub__ to return a tuple

This would save you pokintg about inside the Point objects 
in line which is a design anti-pattern in OOP terms.

> class Line(object):
>    def length(self):
>        dist_x = abs(self.p2.x - self.p1.x)
>        dist_y = abs(self.p2.y - self.p1.y)

You don;t bneed the abs() since when you square them 
you will always get a positive number.

>        dist_x_squared = dist_x ** 2
>        dist_y_squared = dist_y ** 2
>        line_length = math.sqrt(dist_x_squared + dist_y_squared)
>        return line_length

With __sub__ defined you could write:

def length(self):
     dx,dy = self.p1 - self.p2
     return (dx**2 + dy **2) ** 0.5

Let objects do it to themselves - the law of demeter.

>    def slope(self):
>        dist_y = self.p2.y - self.p1.y
>        dist_x = self.p2.x - self.p1.x
>        line_slope = dist_y/dist_x
>        return line_slope

And this becomes

def slope(self):
       dx,dy = self.p1 - self.p2
       return dy/dx

Just a thought. Get the objects to do the work not 
the using methods

HTH,

-- 
Alan Gauld
Author of the Learn to Program web site
http://www.freenetpages.co.uk/hp/alan.gauld