Hi Joe,
I can reproduce your results on Rakudo_2020.10, but I'm afraid I don't
have much more to say about the ",=" operator since I'm unfamiliar
with it.
Do the "docs" page(s) make more sense changing the phrase
"class-dependent" behavior to "hash-dependent" behavior?
Best, Bill.
On Thu, Nov 26, 2020 at 2:29 PM Joseph Brenner <doom...@gmail.com> wrote:
>
> I was going through the operator list in the documentation the
> other day, and I noticed this one:
>
> postfix ,=
>
> Creates an object that concatenates, in a class-dependent way,
> the contents of the variable on the left hand side and the
> expression on the right hand side:
>
> my %a = :11a, :22b;
> %a ,= :33x;
> say %a # OUTPUT: «{a => 11, b => 22, x => 33}»
>
> I was playing around with this a bit and now I'm wondering what
> it's talking about with that "class-dependent way".
>
> To start with, I've got a small issue with that example:
> that particular pair-input syntax is my least favorite.
> Flipping around the order of key and value when the value is a numeric...?
>
> And it isn't needed to demo the operator, any pair input syntax works.
> I might argue that examples should favor the form that "say" is
> going to spit back to you. This would be clearer at a glance:
>
> my %b = a => 11, b => 22;
> %b ,= x => 33;
> say %b; # OUTPUT: «{a => 11, b => 22, x => 33}»
>
> But where it gets interesting is trying a ,= on something besides
> a hash. Let's try arrays, where I would expect this to push a
> value onto the array:
>
> my @r = 'a', 'b', 'c';
> say @r; # [a b c]
> @r ,= 'd';
> say @r; # (\Array_53270704 = [Array_53270704 d])
> dd @r; # Array @r = ((my @Array_37059224) = [@Array_37059224, "d"])
>
> It's difficult for me to even see what that is or how I would use it:
>
> say "keys: ", @r.keys; # keys: (0 1)
> say @r[0]; # (\Array_44472736 = [Array_44472736 d])
> say @r[1]; # d
>
> So it *does* push a 'd', but it first mangles the original
> contents of the array. It looks like @r[0] now has some sort
> of circular pointer back to @r.
>
> Whatever this "class-dependent" behavior is, I would suggest
> it's a "fail". Could this be a bug?
