metaprogramming_with_define_method

✨ Using Lambdas in Metaprogramming and DSLs

In DSLs or dynamic APIs, inject lambdas into define_method calls to create methods with captured context. This technique builds fluent interfaces and reduces boilerplate significantly.

class ModelBuilder
  def initialize(&block)
    instance_eval(&block)
  end

  def field(name, &transform)
    define_singleton_method(name) do |value|
      transform ? transform.call(value) : value
    end
  end
end

user = ModelBuilder.new do
  field(:upcase) { |v| v.upcase }
  field(:double)  { |v| v * 2 }
end

puts user.upcase("hello") # => "HELLO"
puts user.double(5)       # => 10

Bind service locators or policy checkers via closures for high-level separation of concerns.