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Overriding default gist method
Combined from primary sources listed below.

In Classes and objects§

See primary documentation in context for Overriding default gist method.

Some classes might need their own version of gist, which overrides the terse way they are printed when called to provide a default representation of the class. For instance, exceptions might want to write just the payload and not the full object so that it is clearer what to see what's happened. However, this isn't limited to exceptions; you can do that with every class:

class Cook {
    has @.utensils  is rw;
    has @.cookbooks is rw;

    method cook( $food ) {
        return "Cooking $food";
    }

    method clean_utensils {
        return "Cleaning $_" for @.utensils;
    }

    multi method gist(Cook:U:) { '⚗' ~ self.^name ~ '⚗' }
    multi method gist(Cook:D:) {
        '⚗ Cooks with ' ~ @.utensils.join( " ‣ ") ~ ' using '
          ~ @.cookbooks.map( "«" ~ * ~ "»").join( " and ") }
}

my $cook = Cook.new(
    utensils => <spoon ladle knife pan>,
    cookbooks => ['Cooking for geeks','The French Chef Cookbook']);

say Cook.gist; # OUTPUT: «⚗Cook⚗»
say $cook.gist; # OUTPUT: «⚗ Cooks with spoon ‣ ladle ‣ knife ‣ pan using «Cooking for geeks» and «The French Chef Cookbook»␤»

Usually you will want to define two methods, one for the class and another for class instances; in this case, the class method uses the alembic symbol, and the instance method, defined below it, aggregates the data we have on the cook to show it in a narrative way.