Ruby attr_accessor overshadowing

example.rb

# Illustration of a neat thing that footguns me 1x a year
class Foo
  attr_accessor :params
  attr_reader :val1, :val2, :val3

  def initialize(params: {})
    @params = params.with_indifferent_access

    # The below should either be:
    #
    #   self.params.fetch(:blah, {})
    #   @params.fetch(:blah, {})
    #
    # Or you can use a different attr_accessor/initialize keyword so no name collision
    #
    # The below does not call the attr_accessor, it use a local variable (from the initializer)
    @val1 = params.fetch(:foo, 'oops')
    @val2 = @params.fetch(:foo, 'oops')
    @val3 = self.params.fetch(:foo, 'oops')
  end

  def call
    puts <<~TXT
      params #{params}
      params.class #{params.class}

      val1 #{val1}
      val2 #{val2}
      val3 #{val3}
    TXT
  end
end

x = Foo.new(params: {'foo' => 'bar'})
x.call

__END__
# Output is below
params {"foo"=>"bar"}
params.class ActiveSupport::HashWithIndifferentAccess

val1 oops
val2 bar
val3 bar