Re^2: Perl 6, defining a hash with interpolated string

[Mr_Micawber]

I think I was looking for the interpolating analog of this model for specifying a literal hash pair:

%kv = :LiteralKey<LiteralValue>

[molecules]

The last two of the following examples give you interpolation, but it is more of the "normal" interpolation you would expect in Perl.

use v6;


my %kv1 = :LiteralKey<LiteralValue>;

say :%kv1.perl;



my %kv2 = <LiteralKey>,<LiteralValue>;

say :%kv2.perl;



my $var3 = 'Literal';
my %kv3  = "{$var3}key",'LiteralValue';

say :%kv3.perl;



my $var4 = 'LiteralKey';
my %kv4  = "$var4",'LiteralValue';

say :%kv4.perl;

gives you

"kv1" => {"LiteralKey" => "LiteralValue"}
"kv2" => {"LiteralKey" => "LiteralValue"}
"kv3" => {"Literalkey" => "LiteralValue"}
"kv4" => {"LiteralKey" => "LiteralValue"}

[Mr_Micawber]

I noticed playing with this code that the output of .perl differs depending on if the colon is in front of the variable:

say :%kv4.perl; #"kv1" => {"LiteralKey" => "LiteralValue"}
say %kv4.perl;  #{"LiteralKey" => "LiteralValue"}

the colon seems to be plucking the Hash's name and creating a Pair with it.

[molecules]

Yes that is correct.

my $name='Larry';
my $pair = :$name;
say $pair.perl;

Outputs:

"name" => "Larry"



UPDATE:
This is especially useful for named parameters in subroutine declarations.

For example:

use v6;

foo(  B => 'there',A => 'howdy');

sub foo(Str :$A, Str :$B){
        say "Named parameter A is '$A'";
        say "Named parameter B is '$B'";

}