Vyacheslav Maslov wrote: > So, the main question is why using syntax like [X] python constuct list with > one item, but when i try to construct tuple with one item using similar > syntax (X) python do nothing?
Because what determines that you actually have a tuple is the comma, not the parenthesis. See the following explanations. Both empty tuples, one without arguments, the second also without arguments: >>> tuple() () >>> tuple(()) () Constructing a tuple with one argument, which is an iterable (actually, another tuple): >>> tuple((4,)) (4,) The following is not allowed, because you're calling tuple() with one argument, an int 4, and ints are not iterable. >>> tuple(4,) Traceback (most recent call last): File "<stdin>", line 1, in <module> TypeError: 'int' object is not iterable Note how we also can construct tuples by using the commas, and not the parenthesis: >>> 3,4 (3, 4) >>> a = 5,6 >>> type(a) <type 'tuple'> >>> c,d = a >>> c 5 >>> d 6 Regards, -- . Facundo . Blog: http://www.taniquetil.com.ar/plog/ PyAr: http://www.python.org/ar/ -- http://mail.python.org/mailman/listinfo/python-list
