[Tutor] Trouble with exercise regarding classes

[Andrew Martin]

All I want to do is add a line that displays that maximum height the
cannonball reaches. I created a variable zenith to store the highest y
value. I then wanted to compare the current y value of the cannonball to
zenith while the cannonballs y value is greater than zero. If the
cannonballs current y value is greater than zenith, I want to have the
current value replace zenith. Finally, once the cannonball has reaches y =
0, I wanted the program to write out the value for zenith.

I want to compare zenith, a floating point number, with the current y value?
I thought the current y value could be retrieved by Projectile.getY. And how
do I call the getY using the instance?



On Wed, Aug 25, 2010 at 7:24 PM, Alan Gauld <alan.gauld at btinternet.com>wrote:

>
> "Andrew Martin" <amartin7211 at gmail.com> wrote
>
>
>  However, when I did so I got this error: "TypeError: unbound method getY()
>> must be called with Projectile instance as first argument (got nothing
>> instead) "
>>
>
>  def main():
>>>    angle, vel, h0, time = getInputs()
>>>    cball = Projectile(angle, vel, h0)
>>>
>>
> cball is a Projectile instance
>
>
>     zenith = 0.0
>>>    while cball.getY() >= 0:
>>>
>>
> So this is fine
>
>
>         cball.update(time)
>>>
>>
>
>         if Projectile.getY > zenith:
>>>            zenith = Projectile.getY()
>>>
>>
> But what are you doing here?
> You are trying to compare the getY method of the class with a floating
> point number?
> Then you call getY using the class rather than the instance?
> I'm confused - and so is Python...
>
>
> --
> Alan Gauld
> Author of the Learn to Program web site
> http://www.alan-g.me.uk/
>
>
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