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module Finitio
#
# Helper class for tuple and relation attributes.
#
# An attribute is simply a `(name: AttrName, type: Type)` pair, where the
# type is a Finitio type.
#
class Attribute
include Metadata
def initialize(name, type, required = true, metadata = nil)
unless name.is_a?(Symbol)
raise ArgumentError, "Symbol expected for attribute name, got `#{name}`"
end
unless type.is_a?(Type)
raise ArgumentError, "Type expected for attribute domain, got `#{type}`"
end
@name, @type, @required, @metadata = name, type, required, metadata
end
attr_reader :name, :type, :required
alias :required? :required
def optional?
!required?
end
# Fetch the attribute on `arg`, which is expected to be a Hash object.
#
# This method allows working with ruby hashes having either Symbols or
# Strings as keys. It ensures that no Symbol is created by the rest of the
# code, since this would provide a DoS attack vector under MRI.
#
def fetch_on(arg, &bl)
unless arg.respond_to?(:fetch)
raise ArgumentError, "Object responding to `fetch` expected"
end
arg.fetch(name) do
arg.fetch(name.to_s, &bl)
end
end
def to_name
required ? "#{name}: #{type}" : "#{name} :? #{type}"
end
def ==(other)
other.is_a?(Attribute) && name==other.name && \
type==other.type && required==other.required
end
alias :eql? :==
def hash
name.hash ^ type.hash ^ required.hash
end
end # class Attribute
end # module Finitio
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10 entries across 10 versions & 1 rubygems