What do

practices.rb

########
# Hash #
########
def function(opts)
  request = {}
  request[:name] = opts[:name] if opts[:name]
  request[:email] = opts[:email] if opts[:email]
  request[:address] = opts[:name] if opts[:name]
  post_to_service(request)
end

# Call it with:
function(name: "Bob", email: "test@foo.bar", address: "123 Fake St.")
function(name: "Bob", email: "test@foo.bar", address: nil)

################
# List of args #
################
def function(name, email = "bar@baz.qux", address = nil)
  request = {}
  request[:name] = name
  request[:email] = email
  request[:address] = address if address.present?
  post_to_service(request)
end

# Call it with
function(name = "Bob", email = "test@foo.bar", address = "123 Fake St.")
function(name = "Bob", email = "test@foo.bar")
function(name = "Bob")

You can really just accomplish the problem like below. Basically all you are doing in your first 'function' is cloning the hash into another hash called request. Just accept the param as hash and default the param to a empty hash and whatever keys aren't passed won't be passed and the opposite goes for the opposite.

def function(request = {})
    post_to_service(request)
end