Cameron <[EMAIL PROTECTED]> writes:
> I was reading this <a href="this http://www.paulgraham.com/icad.html";>Paul
> Graham article</a> and he builds an accumuator generator function in
> the appendix. His looks like this:
>
> <pre>
> def foo(n):
> s = [n]
> def bar(i):
> s[0] += i
> return s[0]
> return bar
> </pre>
>
> Why does that work, but not this:
>
> <pre>
> def foo(n):
> s = n
> def bar(i):
> s += i
> return s
> return bar
> </pre>
Others have explained why, but this looks like "pythonized LISP" to
me. I would rather use a generator function:
def foo(n):
while True:
n += yield n
Although the problem is that you can't send it values the first time
round!
>>> bar = foo('s')
>>> bar.next()
's'
>>> bar.send('p')
'sp'
>>> bar.send('am')
'spam'
But:
>>> bar = foo(3)
>>> bar.send(2)
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
TypeError: can't send non-None value to a just-started generator
>>>
--
Arnaud
--
http://mail.python.org/mailman/listinfo/python-list
