For ideas like this it is best to discuss them on python-ideas.
I'll also mention that this idea has been brought up at least twice before:
search for threads about itertools and single() or first() (if I remember
correctly).
On Mon, Jul 27, 2020 at 12:07 PM Noam Yorav-Raphael
Hi,
There's a simple function that I use many times, and I think may be a good fit to be added to itertools. A function that gets an iterator, and if it has exactly one element returns it, and otherwise raises an exception. This is very useful for cases where I do some sort of query that I expect to get exactly one result, and I want an exception to be raised if I'm wrong. For example:
jack = one(p for p in people if p.id == '1234')
sqlalchemy already has such a function for queries: https://docs.sqlalchemy.org/en/13/orm/query.html#sqlalchemy.orm.query.Query....
This is my implementation:
def one(iterable): it = iter(iterable) try: r = next(it) except StopIteration: raise ValueError("Iterator is empty") try: next(it) except StopIteration: return r else: raise ValueError("Iterator has more than one item")
What do you think?
Thanks, Noam _______________________________________________ Python-Dev mailing list -- python-dev@python.org To unsubscribe send an email to python-dev-leave@python.org https://mail.python.org/mailman3/lists/python-dev.python.org/ Message archived at https://mail.python.org/archives/list/python-dev@python.org/message/D52MPKLI... Code of Conduct: http://python.org/psf/codeofconduct/