Re: [pygame] When to use a constant

[Eric Burgess <eric@big-brain.org>]

Jon Doda wrote:

> Using a class is an interesting idea, which I may look into further. 
> Right now, however, my code involves a number of for-loops and list 
> comprehensions which can act on any set of components (which is the 
> only reason I'm using a list) and I'm not sure how I could replace 
> them without introducing a lot of duplicate code.
>
> As an example, I have a lot of constructs similar to this:
>
> def apply_force(self, force, interval):
>         """Return the change in velocity caused by a force.
>         """
>
>         return [(force[n] / self.mass) * interval for n in range(2)]
>
> And while there's plenty of ways to do the same thing, I can't think 
> of any that are nearly as simple and clean.  Maybe I just like list 
> comprehensions too much :).

I've used complex numbers before.  For the above, you have:

return force / self.mass * interval

...which is very clean.  You can add two complex numbers, multiply a 
complex by a scalar, and take the abs() of a complex, and get the 
results you expect for a vector (abs corresponds to the magnitude). 
Using .real for X and .imag for Y isn't all that pretty, getattr and 
setattr can save you from that.