On Wed, Mar 23, 2016 at 12:14 PM, Steven D'Aprano <st...@pearwood.info> wrote:
>> I mean, is a function allowed to still return True or False, or just
>> False? (Or perhaps just nothing if the exception mechanism can signal
>> either.)
>
>
> You can answer this question yourself by looking at what functions are
> provided in the standard library and built-ins:
>
> py> "hello world".find("goodbye")
> -1
> py> "hello world".startswith("goodbye")
> FalseTo add to the "experiment" advice, a general rule of thumb: Any function/method that appears to be asking a yes/no question should be happy to return True/False for the two answers. It can still raise if the question doesn't make sense: >>> "hello world".startswith(3.14159) Traceback (most recent call last): File "<stdin>", line 1, in <module> TypeError: startswith first arg must be str or a tuple of str, not float >>> "hello world".startswith(b"\x41") Traceback (most recent call last): File "<stdin>", line 1, in <module> TypeError: startswith first arg must be str or a tuple of str, not bytes ChrisA -- https://mail.python.org/mailman/listinfo/python-list
