Filtering out non-readable characters

Bengt Richter bokr at
Sun Jul 24 07:04:09 CEST 2005

On Sun, 17 Jul 2005 15:42:08 -0600, Steven Bethard <steven.bethard at> wrote:

>Bengt Richter wrote:
>> Thanks for the nudge. Actually, I know about generator expressions, but
>> at some point I must have misinterpreted some bug in my code to mean
>> that join in particular didn't like generator expression arguments,
>> and wanted lists.
>I suspect this is bug 905389 [1]:
> >>> def gen():
>...     yield 1
>...     raise TypeError('from gen()')
> >>> ''.join([x for x in gen()])
>Traceback (most recent call last):
>   File "<interactive input>", line 1, in ?
>   File "<interactive input>", line 3, in gen
>TypeError: from gen()
> >>> ''.join(x for x in gen())
>Traceback (most recent call last):
>   File "<interactive input>", line 1, in ?
>TypeError: sequence expected, generator found
>I run into this every month or so, and have to remind myself that it 
>means that my generator is raising a TypeError, not that join doesn't 
>accept generator expressions...

That must have been it, thanks.

Bengt Richter

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