Bizarre behavior with mutable default arguments

[Istvan Albert]

On Dec 30, 11:26 am, George Sakkis <george.sak... at gmail.com> wrote:

> I'm with you on this one; IMHO it's one of the relatively few language
> design missteps of Python, favoring the rare case as the default
> instead of the common one.

George, you pointed this out this link in a different thread

http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/521877

how would you rewrite the code below if you could not use mutable
default arguments (global variables not accepted)? Maybe there is a
way, but I can't think of it as of now.

---------------------------------------

def blocks(s, start, end):
    def classify(c, ingroup=[0]):
        klass = c==start and 2 or c==end and 3 or ingroup[0]
        ingroup[0] = klass==1 or klass==2
        return klass
    return [tuple(g) for k, g in groupby(s, classify) if k == 1]

print blocks('the {quick} brown {fox} jumped', start='{', end='}')