class ValueObjAt is ObjAt { }

A subclass of ObjAt that should be used to indicate that a class produces objects that are value types (in other words: are immutable after they have been initialized.

my %h = a => 42;        # mutable Hash
say %h.WHICH;           # OUTPUT: «ObjAt.new("Hash|1402...888")␤»

my %m is Map = a => 42; # immutable Map
say %m.WHICH;           # OUTPUT: «ValueObjAt.new("Map|AAF...09F61F")␤»

If you create a class that should be considered a value type, you should add a WHICH method to that class that returns a ValueObjAt object, for instance:

class YourClass {
    has $.foo;  # note these are not mutable
    has $.bar;

    method WHICH() {
        ValueObjAt.new("YourClass|$!foo|$!bar");
    }
}

Note that it is customary to always start the identifying string with the name of the object, followed by a "|". This to prevent confusion with other classes that may generate similar string values: the name of the class should then be enough of a differentiator to prevent collisions.

Type Graph

Routines supplied by class ObjAt

ValueObjAt inherits from class ObjAt, which provides the following routines:

(ObjAt) infix eqv

Defined as:

multi sub infix:<eqv>(ObjAt:D $a, ObjAt:D $b)

Returns True if the two ObjAt are the same, that is, if the object they identify is the same.

my @foo = [2,3,1];
my @bar := @foo;
say @foo.WHICH eqv @bar.WHICH; # OUTPUT: «True␤»