On 5/20/06, Nick Coghlan <[EMAIL PROTECTED]> wrote: > Assume the following is true for a type annotation system: > (T,) is equivalent to tuple[T] > (T1, T2) is equivalent to tuple[T1, T2] > (T1, T2, T3) is equivalent to tuple[T1, T2, T3] > > This fits in with how tuples are typically intended to be used (small > collections of heterogeneous data), but how do I use this system to spell the > type annotation for a tuple of unknown length containing only T instances? > > I'd say "that's what lists are for", except that the CPython core uses tuples > as homogeneous containers of unknown length in several places. For example, > the sequence used to hold the additional arguments to a function is a tuple. > So I would expect the type annotation in "*args : T" to be implicitly > translated to "tuple[T]". Similarly, I would expect the type description for > both __mro__ and __bases__ to be "tuple[type]".
This is something I've been meaning to bring up: if we're serious about the "tuples = fixed-length collections, lists = unknown-length collections" distinction, then the CPython core should switch over to this mindset as well. The fact that Python 2.x uses a tuple for *varargs has caused me to jump through a number of hoops in my own typecheck package. If there's interest, I can put together a separate PEP on this issue that lists all the places where tuples would need to be changed to lists. Collin Winter _______________________________________________ Python-3000 mailing list Python-3000@python.org http://mail.python.org/mailman/listinfo/python-3000 Unsubscribe: http://mail.python.org/mailman/options/python-3000/archive%40mail-archive.com
