Dynamically defined setter methods using define_method?

Question

I use a lot of iterations to define convenience methods in my models, stuff like:

PET_NAMES.each do |pn|
define_method(pn) do
...
...
end

but I

Answer 1

Shoertly if you need it inside one class/module: I use hash but you can put there array of elements etc.

PETS = {
  "cat" => "meyow",
  "cow" => "moo",
  "dog" => "ruff"
}

def do_smth1(v)
...
end

def do_smth(sound,v)
...
end

#getter
PETS.each{ |k,v| define_method(k){ do_smth1(v) } }

#setter
PETS.each{ |k,v| define_method("#{k}="){|sound| do_smth2(sound, v) }

Answer 2

Here's a fairly full example of using define_method in a module that you use to extend your class:

module VerboseSetter
  def make_verbose_setter(*names)
    names.each do |name|
      define_method("#{name}=") do |val|
        puts "@#{name} was set to #{val}"
        instance_variable_set("@#{name}", val)
      end
    end
  end
end

class Foo
  extend VerboseSetter

  make_verbose_setter :bar, :quux
end

f = Foo.new
f.bar = 5
f.quux = 10

Output:

@bar was set to 5
@quux was set to 10

You were close, but you don't want to include the argument of the method inside the arguments of your call to define_method. The arguments go in the block you pass to define_method.