On Wed, Jul 5, 2017 at 11:34 AM, Chris Barker <chris.barker@noaa.gov> wrote:

On Sun, Jun 25, 2017 at 6:20 PM, Mikhail V <mikhailwas@gmail.com> wrote:

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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:

[veering off-topic] I've implemented mutable integers as part of the gmpy2 library. The eXperimental MPZ (xmpz) type breaks many of the normal rules. Mutable

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a=gmpy2.xmpz(1) b=a a+=1 a xmpz(2) b xmpz(2)

Direct access to individual bits

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a=gmpy2.xmpz(123) a[0] 1 a[1] 1 a[0]=0 a xmpz(122)

Iterating over bits

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a=gmpy2.xmpz(104) bin(a) '0b1101000' list(a.iter_bits()) [False, False, False, True, False, True, True] list(a.iter_clear()) [0, 1, 2, 4] list(a.iter_set()) [3, 5, 6]

I'm not sure how useful it really is but it was fun to write. :) casevh