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Contents
module Alba
# Representing typed attributes to encapsulate logic about types
class TypedAttribute
# @param name [Symbol, String]
# @param type [Symbol, Class]
# @param converter [Proc]
def initialize(name:, type:, converter:)
@name = name
@type = type
@converter = case converter
when true then default_converter
when false, nil then null_converter
else converter
end
end
# @param object [Object] target to check and convert type with
# @return [String, Integer, Boolean] type-checked or type-converted object
def value(object)
value, result = check(object)
result ? value : @converter.call(value)
rescue TypeError
raise TypeError, "Attribute #{@name} is expected to be #{@type} but actually #{display_value_for(value)}."
end
private
def check(object)
value = object.__send__(@name)
type_correct = case @type
when :String, ->(klass) { klass == String } then value.is_a?(String)
when :Integer, ->(klass) { klass == Integer } then value.is_a?(Integer)
when :Boolean then [true, false].include?(value)
else
raise Alba::UnsupportedType, "Unknown type: #{@type}"
end
[value, type_correct]
end
def default_converter
case @type
when :String, ->(klass) { klass == String }
->(object) { object.to_s }
when :Integer, ->(klass) { klass == Integer }
->(object) { Integer(object) }
when :Boolean
->(object) { !!object }
else
raise Alba::UnsupportedType, "Unknown type: #{@type}"
end
end
def null_converter
->(_) { raise TypeError }
end
def display_value_for(value)
value.nil? ? 'nil' : value.class.name
end
end
end
Version data entries
5 entries across 5 versions & 1 rubygems