Hi, I was experimenting with the swap proc of the system module (here's the doc) since I need it in a uni project and I encountered a behavior that confuses me. If i go to the Nim Playground and I execute the following program:
from algorithm import fill
proc swapper[R,T](arr: var array[R, T]) =
let oldaddr = arr.addr
var support: array[R,T]
support.fill(1)
echo arr.addr == oldaddr
swap(support, arr)
echo arr.addr == oldaddr
echo support.addr == oldaddr
echo arr
when isMainModule:
var arr = [1,2,3,4,5,6,7,8,9]
echo arr
arr.swapper
echo arr
[1, 2, 3, 4, 5, 6, 7, 8, 9]
true
false
false
[1, 1, 1, 1, 1, 1, 1, 1, 1]
[1, 2, 3, 4, 5, 6, 7, 8, 9]
It's a bug. :-)
This works:
from algorithm import fill
type
O = object
a: array[9, int]
proc swapper(arr: var O) =
#let oldaddr = arr.addr
var support: O
support.a.fill(1)
#echo arr.addr == oldaddr
swap(support, arr)
#echo arr.addr == oldaddr
#echo support.addr == oldaddr
#echo arr
when isMainModule:
var arr = O(a: [1,2,3,4,5,6,7,8,9])
echo arr
arr.swapper
echo arr
is there any python like syntax for swap
a,b=b,a and a,b=b,a+b (fibonachi case)
(a, b) = (b, a)