- "is => 'ro', 'rw', 'bare'"
-
This provides a shorthand for specifying the "reader", "writer", or
"accessor" names. If the attribute is read-only ('ro') then it will
have a "reader" method with the same attribute as the name.
If it is read-write ('rw') then it will have an "accessor" method
with the same name. If you provide an explicit "writer" for a
read-write attribute, then you will have a "reader" with the same
name as the attribute, and a "writer" with the name you provided.
Use 'bare' when you are deliberately not installing any methods
(accessor, reader, etc.) associated with this attribute; otherwise,
Moose will issue a deprecation warning when this attribute is added to a
metaclass.
- "isa => Type"
-
This option accepts a type. The type can be a string, which should be
a type name. If the type name is unknown, it is assumed to be a class
name.
This option can also accept a Moose::Meta::TypeConstraint object.
If you also provide a "does" option, then your "isa" option must
be a class name, and that class must do the role specified with
"does".
- "does => Role"
-
This is short-hand for saying that the attribute's type must be an
object which does the named role.
This option is not yet supported.
- "coerce => Bool"
-
This option is only valid for objects with a type constraint
("isa"). If this is true, then coercions will be applied whenever
this attribute is set.
You can make both this and the "weak_ref" option true.
- "trigger => CodeRef"
-
This option accepts a subroutine reference, which will be called after
the attribute is set.
- "required => Bool"
-
An attribute which is required must be provided to the constructor. An
attribute which is required can also have a "default" or "builder",
which will satisfy its required-ness.
A required attribute must have a "default", "builder" or a
non-"undef" "init_arg"
- "lazy => Bool"
-
A lazy attribute must have a "default" or "builder". When an
attribute is lazy, the default value will not be calculated until the
attribute is read.
- "weak_ref => Bool"
-
If this is true, the attribute's value will be stored as a weak
reference.
- "auto_deref => Bool"
-
If this is true, then the reader will dereference the value when it is
called. The attribute must have a type constraint which defines the
attribute as an array or hash reference.
- "lazy_build => Bool"
-
Setting this to true makes the attribute lazy and provides a number of
default methods.
has 'size' => (
is => 'ro',
lazy_build => 1,
);
is equivalent to this:
has 'size' => (
is => 'ro',
lazy => 1,
builder => '_build_size',
clearer => 'clear_size',
predicate => 'has_size',
);