Generators can only yield ints?

[Steven D'Aprano]

On Fri, 22 Aug 2008 15:44:15 -0700, defn noob wrote:

> def letters():
> 	a = xrange(ord('a'), ord('z')+1)
> 	B = xrange(ord('A'), ord('Z')+1)
> 	while True:
> 		yield chr(a)
> 		yield chr(B)
> 
> 
>>>> l = letters()
>>>> l.next()
> 
> Traceback (most recent call last):
>   File "<pyshell#225>", line 1, in <module>
>     l.next()
>   File "<pyshell#223>", line 5, in letters
>     yield chr(a)
> TypeError: an integer is required
>>>>
>>>>
> 
> Any way to get around this?

Yes, write code that isn't buggy :)

Generators can return anything you want. Your problem is that you're 
passing an xrange object to chr() instead of an int. Try this:

def letters():
    a = xrange(ord('a'), ord('z')+1)
    B = xrange(ord('A'), ord('Z')+1)
    for t in zip(a, B):
        yield chr(t[0])
        yield chr(t[1])

But (arguably) a better way is:

def letters():
    from string import ascii_letters as letters
    for a,b in zip(letters[0:26], letters[26:]):
        yield a
        yield b


Note that it is important to use ascii_letters rather than letters, 
because in some locales the number of uppercase and lowercase letters 
differ.


-- 
Steven