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've never been able to dynamically define setter methods, ie:

def pet_name=(name)
...
end

using define_method like so:

define_method("pet_name=(name)") do
...
end

Any ideas? Thanks in advance.

Answer 1

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.