[Tutor] line class

[Marc Tompkins]

On Tue, Jul 8, 2008 at 3:29 PM, Christopher Spears <cspears2002 at yahoo.com>
wrote:

> I have been reading everyone's comments on my line class.  I have decided
> to implement some of the suggestions.  Someone suggested that I create a
> Point.__cmp__ method.  Here is what I have so far:
>
> def __cmp__(self, other):
>        if self.x == other.x and self.y == other.y:
>            return 0
>        elif self.x < other.x and self.y < other.y:
>            return -1
>        elif self.x > other.x and self.y > other.y:
>            return 1
>
> Figuring out the results for the above situations was easy.  However, what
> should I do with the following situations:
> self.x > other.x and self.y < other.y
> self.x < other.x and self.y > other.y
>

Sorry to jump in late - I missed the first part of the discussion - but what
do you want to achieve with a Point.__cmp__ method?

Is it just to determine whether two points are identical - in which case I'd
write it like so:
def __cmp__(self, other):
    if (self.x == other.x) and (self.y == other.y):
        return True
    else:
        return False


Or are you trying to determine the slope of the line between two points, in
which case I'd write it like this:
def __cmp__(self, other):
    if self.x == other.x:
        return False # points are identical, or one above the other - slope
is undefined
    else:
        return (self.y - other.y) / (self.x - other.x) # rise over run

or... or... or...  First decide what you want out of it, then write the
function/method to give you the result you want.

-- 
www.fsrtechnologies.com
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