On Sun, Jun 25, 2017 at 6:20 PM, Mikhail V <mikhailwas@gmail.com> wrote:
And it reminded me times starting with Python and wondering why I can't simply write something like:
def move(x,y): x = x + 10 y = y + 20 move(x,y)
Instead of this:
def move(x,y): x1 = x + 10 y1 = y + 20 return x1,y1 x,y = move(x,y)
you CAN do that, if x and y are mutable types. I've found that when folk want this behavior (often called "pass by reference" or something), what they really want in a mutable number. And you can make one of those if you like -- here's a minimal one that can be used as a counter: In [12]: class Mint(): ...: def __init__(self, val=0): ...: self.val = val ...: ...: def __iadd__(self, other): ...: self.val += other ...: return self ...: ...: def __repr__(self): ...: return "Mint(%i)" % self.val so now your move() function can work: In [17]: def move(x, y): ...: x += 1 ...: y += 1 In [18]: a = Mint() In [19]: b = Mint() In [20]: move(a, b) In [21]: a Out[21]: Mint(1) In [22]: b Out[22]: Mint(1) I've seen recipes for a complete mutable integer, though Google is failing me right now. This does come up fairly often -- I usually think there are more Pythonic ways of solving the problem - like returning multiple values, but maybe it has its uses. -CHB -- Christopher Barker, Ph.D. Oceanographer Emergency Response Division NOAA/NOS/OR&R (206) 526-6959 voice 7600 Sand Point Way NE (206) 526-6329 fax Seattle, WA 98115 (206) 526-6317 main reception Chris.Barker@noaa.gov