Object help
killsto
size, active. So each ball is an object.
How do I make the object without specifically saying ball1 = ball()?
Because I don't know how many balls I want; each time it is different.
The balls are to be thrown in from the outside of the screen. I think
you get that is enough information.
This doesn't directly pertain to balls, I have wanted to do something
like this for many different things but didn't know how.
I would think something like:
def newball():
x = last_named_ball + 1
ball_x = ball(size, etc) # this initializes a new ball
return ball_x
But then that would just name a ball ball_x, not ball_1 or ball_2.
Is it possible?
Chris Rebert
> I have a class called ball. The members are things like position,
> size, active. So each ball is an object.
Class names should use CamelCase, so it should be `Ball`, not `ball`.
> How do I make the object without specifically saying ball1 = ball()?
> Because I don't know how many balls I want; each time it is different.
>
> The balls are to be thrown in from the outside of the screen. I think
> you get that is enough information.
>
> This doesn't directly pertain to balls, I have wanted to do something
> like this for many different things but didn't know how.
>
> I would think something like:
>
> def newball():
> x = last_named_ball + 1
> ball_x = ball(size, etc) # this initializes a new ball
> return ball_x
>
> But then that would just name a ball ball_x, not ball_1 or ball_2.
>
> Is it possible?
Yes, but only using deep dark black magic. Just use a list of Ball
objects instead.
Example:
the_balls = [Ball(size, etc) for i in range(number_of_balls)]
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Steven D'Aprano
This is the TOTALLY wrong approach.
Instead of having named balls, have a list of balls.
balls = [] # no balls yet
balls.append(Ball()) # one ball comes in from off-screen
balls.append(Ball()) # and a second
del balls[0] # the first ball got stuck in a tree
balls = [] # all the balls were swept up in a hurricane and lost
balls = [Ball(), Ball(), Ball(), Ball()] # four balls come in
balls.append(Ball()) # and a fifth
for b in balls:
print b.colour # print the colour of each ball
and so forth.
--
Steven
killsto
Thanks. That makes sense. It helps a lot. Although, you spelled color
wrong :P.
Just curious, is there another way? How would I do this in c++ which
is listless IIRC.
James Mills
> Thanks. That makes sense. It helps a lot. Although, you spelled color
> wrong :P.
color
colour
They are both correct depending on what
country you come from :)
> Just curious, is there another way? How would I do this in c++ which
> is listless IIRC.
Why are you asking us ? We're Python devs/programmers
not C++
cheers
James
PS: I wouldn't touch C++ with a 10-foot pole
Chris Rebert
> On Jan 11, 2:20 pm, Steven D'Aprano <st...@REMOVE-THIS-
> cybersource.com.au> wrote:
>> On Sun, 11 Jan 2009 14:06:22 -0800, killsto wrote:
>> > I have a class called ball. The members are things like position, size,
>> > active. So each ball is an object.
>>
>> > How do I make the object without specifically saying ball1 = ball()?
>> > Because I don't know how many balls I want; each time it is different.
>> This is the TOTALLY wrong approach.
>>
>> Instead of having named balls, have a list of balls.
> Just curious, is there another way? How would I do this in c++ which
> is listless IIRC.
If *I* recall correctly, the STL has a `vector` type which is the
equivalent of Python's `list`.
Cheers,
Chris
Terry Reedy
> Just curious, is there another way? How would I do this in c++ which
> is listless IIRC.
If you do not have 0) built-in expandable arrays, as in Python, one can
1) program (or find) the equivalent of Python lists;
2) use linked-lists (as long as one does not need O(1) random access);
3) pick a maximum number of items, either for the app or for the run,
and allocate space for that.
Python enthusiasts include those who see the virtue of option 0).
John Machin
> On Jan 11, 2:20 pm, Steven D'Aprano <st...@REMOVE-THIS-cybersource.com.au> wrote:
> > On Sun, 11 Jan 2009 14:06:22 -0800, killsto wrote:
> > > I have a class called ball. The members are things like position, size,
> > > active. So each ball is an object.
>
> > > How do I make the object without specifically saying ball1 = ball()?
> > > Because I don't know how many balls I want; each time it is different.
>
Or some other collection or container of objects (e.g. a dict or a
queue), depending on what you are trying to simulate.
> > for b in balls:
> > print b.colour # print the colour of each ball
>
> Thanks. That makes sense. It helps a lot. Although, you spelled color
> wrong :P.
At this time of day you are likely to find yourself communicating with
Australians. Get used to it :-)
Cheers,
John
killsto
> > Thanks. That makes sense. It helps a lot. Although, you spelled color
> > wrong :P.
>
> At this time of day you are likely to find yourself communicating with
> Australians. Get used to it :-)
>
> Cheers,
> John
I was kidding. IMO, we Americans should spell color like everyone
else. Heck, use the metric system too while we are at it.
James Mills
> I was kidding. IMO, we Americans should spell color like everyone
> else. Heck, use the metric system too while we are at it.
Yes well why don't you start up a rally and convince
your brand new shiny government to catch up with
the rest of the world! :)
cheers
James
Steve Holden
>> wrong :P.
>
> colour
>
> They are both correct depending on what
> country you come from :)
>
regards
Steve
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