Code

class Code is Any does Callable { ... }

Code is the ultimate base class of all code objects in Perl 6. It exposes functionality that all code objects have. While thunks are directly of type Code, most code objects (such as those resulting from blocks, subroutines or methods) will be of some subclass of Code.

Methods

ACCEPTS

multi method ACCEPTS(Code:D: Mu $topic)

Usually calls the code object and passes $topic as an argument. However, when called on a code object that takes no arguments, the code object is invoked with no arguments and $topic is dropped. The result of the call is returned.

arity

method arity(Code:D:) returns Int:D

Returns the minimum number of positional arguments that must be passed in order to call the code object. Any optional or slurpy parameters in the code object's Signature do not contribute, nor do named parameters.

sub argless() { }
sub args($a, $b?) { }
sub slurpy($a, $b, *@c) { }
say &argless.arity;             # 0
say &args.arity;                # 1
say &slurpy.arity;              # 2

count

method count(Code:D:) returns Real:D

Returns the maximum number of positional arguments that may be passed when calling the code object. For code objects that can accept any number of positional arguments (that is, they have a slurpy parameter), count will return Inf. Named parameters do not contribute.

sub argless() { }
sub args($a, $b?) { }
sub slurpy($a, $b, *@c) { }
say &argless.count;             # 0
say &args.count;                # 2
say &slurpy.count;              # Inf

signature

multi method signature(Code:D:) returns Signature:D

Returns the Signature object for this code object, which describes its parameters.

Str

multi method Str(Code:D:) returns Str:D

Returns the name of the code object.

sub marine() { }
say ~&marine;   # marine
Full-size type graph image as SVG

Methods supplied by class Any

Code inherits from class Any, which provides the following methods:

ACCEPTS

multi method ACCEPTS(Any:D: Mu $other)

Returns True if $other === self (i.e. it checks object identity).

any

Interprets the invocant as a list and creates an any-Junction from it.

all

Interprets the invocant as a list and creates an all-Junction from it.

one

Interprets the invocant as a list and creates an one-Junction from it.

none

Interprets the invocant as a list and creates an none-Junction from it.

Methods supplied by class Mu

Code inherits from class Mu, which provides the following methods:

defined

multi sub    defined(Mu) returns Bool:D
multi method defined()   returns Bool:D

Returns False on the type object, and True otherwise.

Bool

multi sub    Bool(Mu) returns Bool:D
multi method Bool()   returns Bool:D

Returns False on the type object, and True otherwise.

Str

multi method Str()   returns Str

Returns a string representation of the invocant, intended to be machine readable.

gist

multi sub    gist(Mu) returns Str
multi method gist()   returns Str

Returns a string representation of the invocant, optimized for fast recognition by humans.

The default gist method in Mu re-dispatches to the perl method, but many built-in classes override it to something more specific.

perl

multi sub    perl(Mu) returns Str
multi method perl()   returns Str

Returns a Perlish representation of the object (i.e., can usually be re-parsed to regenerate the object).

clone

method clone(*%twiddles)

Creates a shallow clone of the invocant. If named arguments are passed to it, their values are used in every place where an attribute name matches the name of a named argument.

new

multi method new(*%attrinit)

Default method for constructing (create + initialize) new objects of a class. This method expects only named arguments which are then used to initialize attributes with accessors of the same name.

Classes may provide their own new method to override this default.

bless

method bless(*%attrinit) returns Mu:D

Lower-level object construction method than new.

Creates a new object of the same type as the invocant, uses the named arguments to initialize attributes, and returns the created object.

You can use this method when writing custom constructors:

class Point {
    has $.x;
    has $.y;
    multi method new($x, $y) {
        self.bless(:$x, :$y);
    }
}
my $p = Point.new(-1, 1);

(Though each time you write a custom constructor, remember that it makes subclassing harder).

CREATE

method CREATE() returns Mu:D

Allocates a new object of the same type as the invocant, without initializing any attributes.

print

multi method print() returns Bool:D

Prints value to $*OUT after stringification using .Str method without newline at end.

say

multi method say() returns Bool:D

Prints value to $*OUT after stringification using .gist method with newline at end.

ACCEPTS

multi method ACCEPTS(Mu:U: $other)

Performs a type check. Returns True if $other conforms to the invocant (which is always a type object or failure).

This is the method that is triggered on smart-matching against type objects, for example in if $var ~~ Int { ... }.

WHICH

multi method WHICH() returns ObjAt:D

Returns an object of type ObjAt which uniquely identifies the object. Value types override this method which makes sure that two equivalent objects return the same return value from WHICH.