python/course/Chap09/iterator.py

#!/usr/bin/env python3
# Copyright 2009-2017 BHG http://bw.org/

class inclusive_range:
    def __init__(self, *args):
        numargs = len(args)
        self._start = 0
        self._step = 1
        
        if numargs < 1:
            raise TypeError(f'expected at least 1 argument, got {numargs}')
        elif numargs == 1:
            self._stop = args[0]
        elif numargs == 2:
            (self._start, self._stop) = args
        elif numargs == 3:
            (self._start, self._stop, self._step) = args
        else: raise TypeError(f'expected at most 3 arguments, got {numargs}')

        self._next = self._start
    
    def __iter__(self):
        return self

    def __next__(self):
        if self._next > self._stop:
            raise StopIteration
        else:
            _r = self._next
            self._next += self._step
            return _r

def main():
    for n in inclusive_range(25):
        print(n, end=' ')
    print()

if __name__ == '__main__': main()