On 7 fév, 22:16, Steve Holden <[EMAIL PROTECTED]> wrote: > Diez B. Roggisch wrote: > >> self.tasks[:] = tasks > > >> What I do not fully understand is the line "self.tasks[:] = tasks". Why > >> does > >> the guy who coded this did not write it as "self.tasks = tasks"? What is > >> the > >> use of the "[:]" trick ? > > > It changes the list in-place. If it has been given to other objects, it > > might require that. > > Nowadays it's stylistically better to write > > self.tasks = list(tasks) > > as it does just the same
Err... not quite, actually. >>> class Foo(object): ... def __init__(self): ... self.tasks = range(5) ... def test1(self): ... self.tasks[:] = ['a', 'b', 'c'] ... def test2(self): ... self.tasks = list(['d', 'e', 'f']) ... >>> f = Foo() >>> f.tasks [0, 1, 2, 3, 4] >>> alias = f.tasks >>> alias is f.tasks True >>> f.test1() >>> f.tasks ['a', 'b', 'c'] >>> alias ['a', 'b', 'c'] >>> alias is f.tasks True >>> f.test2() >>> f.tasks ['d', 'e', 'f'] >>> alias ['a', 'b', 'c'] >>> alias is f.tasks False >>> > and makes it a little clearer what's going on > (though of course if tasks *isn't* a list it won't do *exactly* the same. > > regards > Steve > -- > Steve Holden +1 571 484 6266 +1 800 494 3119 > Holden Web LLC http://www.holdenweb.com/ -- http://mail.python.org/mailman/listinfo/python-list
