[Tutor] Not sure what I'm doing wrong with these 2 python scripts

[Steven D'Aprano]

On Tue, Nov 19, 2013 at 06:22:32PM -0600, Anton Gilb wrote:
> Not sure what I'm doing wrong, here are the problems and what I have for
> answers so far.

What makes you think you're doing anything wrong? See below for more 
comments.


> 1.)Write the definition of a class  Counter containing:
> An instance variable  named  counter of type  int .
> A constructor that takes one  int argument and assigns its value to  counter
> A method named  increment that adds one to  counter . It does not take
> parameters or return a value.
> A method named  decrement that subtracts one from  counter . It also does
> not take parameters or return a value.
> A method named  get_value that returns the value of the instance variable
> counter .
> 
> class Counter(object):
>     def __init__(self, ct):
>         self.counter = ct
>     def increment(self):
>         self.counter += 1
>     def decrement(self):
>         self.counter -= 1
>     def get_value(self):
>         return self.counter


This looks fine to me, except for a couple of little nit-picks about 
terminology. (If you care about them, feel free to ask, otherwise I'll 
just bite my tongue.) What errors are you getting? Nothing is obvious.


> 2.)Write the definition of a class  WeatherForecast that provides the
> following behavior (methods):
> A method called  set_skies that has one parameter, a String.
> A method called  set_high that has one parameter, an int.
> A method called  set_low that has one parameter, an int.
> A method called  get_skies that has no parameters and that returns the
> value that was last used as an argument in  set_skies .
> A method called  get_high that has no parameters and that returns the value
> that was last used as an argument in  set_high .
> A method called  get_low that has no parameters and that returns the value
> that was last used as an argument in  set_low .
>  No constructor need be defined. Be sure to define instance variables  as
> needed by your "get"/"set" methods.

Again, what errors are you getting?

In this case, I can guess what some of the errors might be. See below.

> class WeatherForecast(object):
>     def __init__ (self):
>         self.skies = ""

The instructions say that you don't have to define a constructor, but 
they don't forbid it. In this case, I think I'd prefer not to include 
the constructor.

(I know I said I wouldn't, but here's one of the nit-picks: __init__  
isn't strictly speaking a constructor, it's an initialiser. Not that the 
difference really matters here.)


>     def get_skies():
>         return self.set_skies

Here, rather than return the skies value, you return the "set_skies" 
method itself. I suggest you look at the first class and consider how 
the get_value method works. You want to return the "skies" value 
instead.


>     def set_skies(self, value)
>         self.skies = value
>     def get_high():
>         return self.set_high

Likewise, here rather than return the high value, you return the 
"set_high" method.

>     def set_high(self, value):
>         self.high = value
>     def get_low():
>         return self.set_low

And likewise again.

>     def set_low(self):
>         self.low = value


Hope this helps,


-- 
Steven