Carbon::Email is no longer serializable

[akadusei]

I include JSON::Serializable in my emails to have them sent in the background with Mel. Since Carbon v0.5, I get a compile error:

Showing last frame. Use --error-trace for full trace.

There was a problem expanding macro 'macro_139862332317072'

Code in /path/to/.crenv/versions/1.11.2/share/crystal/src/json/from_json.cr:271:3

 271 | {% begin %}
       ^
Called macro defined in /path/to/.crenv/versions/1.11.2/share/crystal/src/json/from_json.cr:271:3

 271 | {% begin %}

Which expanded to:

 > 27 |         
 > 28 |           when "io"
 > 29 |             __temp_4884 = self[:io].new(pull)
                                            ^--
Error: wrong number of arguments for 'IO::ARGF#initialize' (given 1, expected 2)

#88 introduced @attachment instance variable in Carbon::Email, a named tuple with one of its members being an IO, which is not serializable.

Is it possible to get rid of the @attachment instance variable? Maybe redefine .attachment macro thus:

macro attachment(value)
    def attachments : Array(Carbon::Attachment)
      {% if @type.methods.map(&.name).includes?("attachments".id) %}
        previous_def | [value]
      {% else %}
        [value]
      {% end %}
    end
  end

Code above is not tested, so I'm not sure if it works. But I'm thinking along the same lines as the callbacks:

carbon/src/carbon/callbacks.cr

Lines 24 to 34 in 0a814fd

	macro before_send
	def before_send
	{% if @type.methods.map(&.name).includes?(:before_send.id) %}
	previous_def
	{% else %}
	super
	{% end %}
	{{ yield }}
	end
	end

Or is there a better way to handle emails with Mel that I'm missing?

[jwoertink]

Ah, yeah. I think we can come up with a patch for this. What do you think @manveru ?