Perl 6 Deep Dive

Using other classes as data types

In the previous code, the address of a house was a free-text string. In more complex applications, it is better to keep addresses as a set of different fields—country, town, zip code, street name, and house number.

One of the possible implementations is adding more attributes to the House class:

class House {    has Int  $.rooms      is rw where {$_ > 0};    has Real $.area       is rw where {$_ > 0};    has Real $.height     is rw where {$_ > 3};    has Int  $.husenumber is rw where {$_ ne ''};    has Int  $.zipcode    is rw where {$_ > 0};    has Str  $.country    is rw where {$_ ne ''};    has Str  $.town       is rw where {$_ ne ''};    has Str  $.street     is rw where {$_ ne ''};}

It works but is not the best solution. Address details may be kept together in ...