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?
