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Re: How to accomplish a method interpolation?

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From:
Siavash
Date:
December 30, 2017 08:54
Subject:
Re: How to accomplish a method interpolation?
Message ID:
87lghklhnq.fsf@gmail.com

What you want is `%items{$item}."$attr"()`.

But if all you want is removing the show's repetition, maybe there are
other ways, for example:

for %!items<ropa femur fósforos>:kv {
    say $^key.tc, ' ', $^value.amount;
}

or if you want all items:

for %!items {
    say .key.tc, ' ', .value.amount;
}

On 2017-12-30 05:13:43 GMT, clasclin . wrote:
> I'm reading a book "Make your own python text adventure" and decided to
> give it a try with perl6. So this code works as expected.
>
> class Bag {
>     has %.items;
>
>     method show {
>         say "ropa ", %!items<ropa>.amount
>             if %!items<ropa>:exists;
>         say "femur ", %!items<femur>.amount
>             if %!items<femur>:exists;
>         say "fósforos ", %!items<fósforos>.amount
>             if %!items<fósforos>:exists;
>     }
> }
>
> I'm using a class called bag as my inventory and trying to keep track of
> items in a hash, so the key is just a name and the value is an object and
> just found that a pattern when I try to list the elements on the screen...
>
> dd %!items
> Hash %!items = {:femur(Items::Femur.new(amount => 1)),
> :fósforos(Items::Matches.new(amount => 3)), :ropa(Items::Cloth.new(amount
> => 4))}
>
> Items has data and the show method does what I expect, then I change the
> code, so I try to add a private method that handdle the pattern and change
> the show method to use the private one.
>
> class Bag {
>     has %.items;
>
>     method !show-item ($msg, $item, $attr) {
>         # dd $msg; dd $item; dd $attr; # all Str
>         say "$msg ", %items{$item}.$attr
>             if %!items{$item}:exists;
>     }
>
>     method show {
>          self!show-item('Ropa', 'ropa', 'amount');
>          ...
>      }
> }
>
> Now I get an error, the line corresponds to the private method
> No such method 'CALL-ME' for invocant of type 'Str'
>
> Try a few variants like return instead of say or things like
>     say "$msg", "%!items{$item}.$attr"; # output: Ropa
> Items::Cloth<94810994868552>.amount
>     say "$msg", $!items{$item}.{$attr}; # output: Type Items::Cloth does
> not support associative indexing.
>     say "$msg", %!items{$item}."{$attr}"; # ouput: gives a compile error
>
> The output I'm expecting is: Ropa 4
> Ropa is the $msg, and 4 corresponds to the value in the attribute amount.
>
> Is there a way to refactor my code? Thanks in advance.

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