decorating methods with default variable values

[JDutil]

What happens when you want to override methods with default values?

For instance:

    # Get current line item for variant if exists
    # Add variant qty to line_item
    def add(variant, quantity = 1, currency = nil, shipment = nil)
      line_item = order.find_line_item_by_variant(variant)
      add_to_line_item(line_item, variant, quantity, currency, shipment)
    end

Guess it must be done like so:

  # Get current line item for variant if exists
  # Add variant qty to line_item
  durably_decorate :add, mode: 'soft', sha: '' do |variant, quantity, currency, shipment|
    quantity ||= 1
    currency ||= nil
    shipment ||= nil
    # If variant is a gift card we say order doesn't already contain it so that each gift card is it's own line item.
    if variant.product.is_gift_card?
      line_item = nil
    else
      line_item = order.find_line_item_by_variant(variant)
    end
    add_to_line_item(line_item, variant, quantity, currency, shipment)
  end

Unless the decorated add remembers the variables default values which I'm guessing it doesn't. Is it even possible?

Or is this going to cause add to always require those variables to be passed in?

[JDutil]

Actually doesn't appear to even work for me. I get:

/usr/local/opt/rbenv/versions/2.0.0-p247/lib/ruby/gems/2.0.0/gems/durable_decorator-0.2.1/lib/durable_decorator/validator.rb:39:in `validate_method_arity': Attempting to override Spree::OrderContents's add with incorrect arity. (DurableDecorator::BadArityError)
    from /usr/local/opt/rbenv/versions/2.0.0-p247/lib/ruby/gems/2.0.0/gems/durable_decorator-0.2.1/lib/durable_decorator/base.rb:35:in `existing_method'
    from /usr/local/opt/rbenv/versions/2.0.0-p247/lib/ruby/gems/2.0.0/gems/durable_decorator-0.2.1/lib/durable_decorator/base.rb:21:in `redefine_instance'
    from /usr/local/opt/rbenv/versions/2.0.0-p247/lib/ruby/gems/2.0.0/gems/durable_decorator-0.2.1/lib/durable_decorator/base.rb:16:in `redefine'
    from /usr/local/opt/rbenv/versions/2.0.0-p247/lib/ruby/gems/2.0.0/gems/durable_decorator-0.2.1/lib/durable_decorator.rb:27:in `durably_decorate'
    from /Users/JDutil/Code/spree_gift_card/app/models/spree/order_contents_decorator.rb:5:in `block in <top (required)>'

[jumph4x]

Oh man, good call. Let me really think about this one.

[jumph4x]

This is a hard one, dude. Literally no ideas.

[JDutil]

Darn I don't have any either. Hopefully someone at SpreeConf can think of something since I'm guessing this is the "problems" part of your lightning talk.

[jumph4x]

Yup :(

[jumph4x]

Actually, this entirely possible.

method_source does, in fact, return the entire method definition that includes the signature. Just need to write a method signature parser. Pretty involved feature. Deferring for now.

[JDutil]

Cool in the meantime this workaround is sufficient https://github.com/jumph4x/durable_decorator#problems do you have any docs you can point me to in case I have time to get to working on this before you?

Also if you could comment on spree/spree#4374 I'd like to close that out if there are no config options you know of that we should add by default.