New assignmens ...

Chris Angelico rosuav at
Wed Oct 27 14:42:45 EDT 2021

On Thu, Oct 28, 2021 at 4:34 AM Christman, Roger Graydon <dvl at> wrote:
> Do you put special code in next_couple() to recognize that the provided arguments
> are actually the first couple so it can return those unmodified, but then require its
> own mental note not to give you an infinite loop forever returning that first couple?
> Do you have to define a special case such as (a,b) = (0,0) or (None,None) to tell
> next_couple that you really want the first one?   That seems a little counter-intuitive
> to have something named "next" need a special input to mean "first",

In some cases, there is a very real special startup value (a seed).
For instance, if we're calculating something relating to the
Mandelbrot set:

# The point we're working with
c = (0.25 + 0.125j)
# Always start here
z = (0 + 0j) # or just 0
while abs(z := z*z+c) < 2:

Though in this case, you don't look for a next_couple, you look for a
single next value, and the other value is constant.

But it all depends on the exact process being done, which is why I've
been asking for real examples.


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