The design of the operators in Perl 6 is very consistent. For example, if you add a new operator to the language, Perl 6 will create a few more to keep the harmony. In this section, we will talk about the so-called meta-operators, the operators over other operators.
The assignment meta-operators (=) use the other operators to create the constructions like +=, ~=, etc. The action of the newly created operators is always equivalent to the verbose code.
If you type $a op= $b, then a compiler will execute the following action: $a = $a op $b.
That means that $x += 2 is equivalent to $x = $x + 2, and $str ~= ‘.’ to $str = $str ~ ‘.’.
Let us now create a new custom operator and see if the assignment meta-operator will be available for us. On purpose, I chose quite an outstanding-looking operator ^_^:
sub infix:<^_^>($a, $b) {
$a ~ '_' ~ $b
}
First, check the simple usage of the new operator with two operands:
say 4 ^_^ 5; # 4_5
Then, let us try the meta-operator form of it: ^_^=:
my $x = 'file'; $x ^_^= 101; say $x; # file_101