[Tutor] Trouble with exercise regarding classes

[Nitin Das]

There are 2 ways to get the ypos value one is cball.ypos and another is
call.getY() both will give u the current ypos.

--nitin

On Thu, Aug 26, 2010 at 7:26 AM, Andrew Martin <amartin7211 at gmail.com>wrote:

> 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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>
>
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