What Moose is providing.

has

has make => ( isa => 'Str', is => 'rw', );

This code creates an object attribute called make.

isa specifies the type constraint. Other examples of isa values are:

• Str - A String.
• Int - An integer.
• Bool - A boolean value.
• An object (e.g. DateTime for a DateTime object.)
• A reference (e.g. ArrayRef)

These can also be mixed. For example, you can specify ArrayRef[DateTime]

is has two valid values: rw, and ro.