Vim's copy() vs deepcopy()

gistfile1.vim

" Barry Arthur, April 2015
"
" copy() vs deepcopy()
"
" copy() - a gets an independent copy of x
" but b gets a copy of the reference to y
" so changes made to b are reflected in y.

let x = {'foo' : 1}
let y = {'bar' : x}

let a = copy(x)
let b = copy(y)

let a.foo = 2
let b.bar.foo = 2

echo a.foo b.bar.foo x.foo y.bar

" deepcopy() - b gets its own independent
" copy of y, including an independent copy
" of the x within it.

let x = {'foo' : 1}
let y = {'bar' : x}

let a = deepcopy(x)
let b = deepcopy(y)

let a.foo = 2
let b.bar.foo = 2

echo a.foo b.bar.foo x.foo y.bar