Simple immutable value objects for ruby
Ruby
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lib
spec
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README.md
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values.gemspec

README.md

Values is a tiny library for creating value objects in ruby. These mostly look like classes created using Struct, but fix two problems with those:

  • Struct constructors can take less than the default number of arguments and set other fields as nil: Point = Struct.new(:x,:y) Point.new(1) => #

  • Structs are also mutable: Point = Struct.new(:x,:y) p = Point.new(1,2) p.x = 2 p.x => 2

Values fixes both of these: Point = Value.new(:x, :y) Point.new(1) => ArgumentError: wrong number of arguments, 1 for 2 from /Users/tcrayford/Projects/ruby/values/lib/values.rb:7:in block (2 levels) in new from (irb):5:in new from (irb):5 from /usr/local/bin/irb:12:in

p = Point.new(1,2)
p.x = 1
=> NoMethodError: undefined method x= for #<Point:0x00000100943788 @x=0, @y=1>
from (irb):6
from /usr/local/bin/irb:12:in <main>

Value does NOT have all the features of Struct (nor is it meant to).