Re: The best way to copy a list?

On 6/18/2025 5:19 AM, Colin Macleod wrote:

Mark Summerfield <m.n.summerfield@gmail.com> posted:

>
I'm coming to Tcl from Python & Go. In Python saying `a = [1, 2, 3]` and
then `b = a` makes `b` a _reference_ to `a` rather than an independent
variable. Now I realise that Tcl doesn't do it that way and that `set a
$b` works fine.

 When I had to do some Python for work, after being familiar with Tcl,
I was quite shocked to find that Python shares values in that way! 😲
 

Me too!
This python feature goes against my favorite rule of language design:
"The principle of least astonishment"
I'd have to say that python gets a low score on that one!
especially how with a=b, you don't even know the type (and thus immutability) of b without looking elsewhere, which can lead to some nasty runtime surprises.