Conditional passing of parameters when creating an instance of a class

I'm refactoring my code and I want to have some logic passed to a parameter when creating an instance of a class. To best describe the problem, I will share some code.

I have this method that takes in an object as an argument.

def common_attributes(klass)
  klass.new(id: some_id, name: some_name, role_id: some_role.id)
end

I want to be able to use this to do something like:

def common_attributes(klass)
  klass.new(id: some_id,
            name: some_name
            role_id: some_role.id unless Module::class)
end

This is because I have several classes inside my module. Two of these classes take the same three arguments i.e id and name, role_id. The other class takes two arguments id and name. Please note these are example values and the implementation may not make sense problem I but what is important is to understand the problem I have.

This is how I would use the function:

common_attributes(MyModule::Myclass)

common_attributes(MyModule::DifferentClass)

common_attributes(MyModule::AnotherDifferentClass)

How will I ensure that the other class that takes fewer arguments receives the required parameters and leaves out what it does not need?

NB I can not edit the classes to include optional parameters.

Solution

You should test for the class of klass inside your method. If, for example, the class that only accepts two attributes is MyModule::Myclass, and everything else accepts tree attributes, then either of these solutions should work:

def common_attributes(klass)
  case klass
  when MyModule::Myclass
    klass.new(id: some_id, name: some_name)
  else
    klass.new(id: some_id, name: some_name, role_id: some_role.id)
  end
end

or:

def common_attributes(klass)
  options = { id: some_id, name: some_name }

  if klass.is_a?(MyModule::Myclass)
    options[:role_id] = some_role.id
  end

  klass.new(**options)
end

The checks can grow to cover more special cases as appropriate.