problem using array of instances

[Don Arnold]

Anton Muhin <antonmuhin at sendmail.ru> wrote in message news:<b2afis$1neh$1 at news.peterlink.ru>...
> zenguyuno at yahoo.com wrote:
> > I'm stuck on this one:
> > 
> > I defined a class, call it boat.
> > 
> > I created a list of instances, call it pop, so pop[i] is an instance of
> > the boat class, and I made pop[0], pop[1], etc., all boats.
> > 
> > The boat class has a method defined, call it go().
> > 
> > I want to define a function and pass i to it.  Then inside the function
> > I want it to call the go() method of the ith boat, like pop[i].next. 
> > This didn't work; Python thinks that pop[i] is an int, and doesn't have
> > a go() method.
> > 
> > I tried passing pop[i] to the function, so it would know that pop[i] was
> > a boat, but that didn't work either.  (same error)
> > 
> > pop, the list of boats, is global.  I put a global statement in the
> > function.
> > 
> > I'm using Python 2.2 with Windows 98.
> > 
> > Thanks
> > 
> > z
> It's almost impossible to understand what is going on. Please, post some 
>   actual code.
> 
> Anton.

seems straightforward to me:

pop = []

class boat:
    def __init__(self, i):
        self.id = i

    def go(self):
        print 'boat #', self.id, 'is going.'

def launch(i):
    global pop

    pop[i].go()

for i in range(10):
    pop.append(boat(i))

for i in range(9,-1,-1):
    launch(i)


[--- output ---]

>>> 
boat # 9 is going.
boat # 8 is going.
boat # 7 is going.
boat # 6 is going.
boat # 5 is going.
boat # 4 is going.
boat # 3 is going.
boat # 2 is going.
boat # 1 is going.
boat # 0 is going.


HTH,
Don