George Dietrich Blacksmoke16

Annotations 2.0 - Design Summary

Problem Statement

Crystal's annotation system lacked tight coupling between annotation types and their runtime representations. Framework authors building validation libraries, ORMs, or serialization tools had to maintain two separate type hierarchies:

An annotation type for compile-time metadata
A corresponding class/struct for runtime logic

This duplication was error-prone and verbose. Users couldn't easily convert annotations to runtime objects or leverage inheritance for annotation hierarchies.

	{% if flag?(:win32) %}
	lib LibC
	STDOUT_HANDLE = 0xFFFFFFF5

	struct Point
	x : UInt16
	y : UInt16
	end

	struct SmallRect

	require "xml"

	lib LibXML
	type XMLSchemaParserCtxtPtr = Void*
	type XMLSchemaValidCtxtPtr = Void*

	struct XMLError
	domain : Int
	code : Int
	message : UInt8*

	@[ADI::Register]
	# Central access point to DB related actions
	class Blog::Services::EntityManager
	@@connection : DB::Database = DB.open ENV["DATABASE_URL"]

	# Each entity has a Repository to store query methods
	# Longer term ofc this could be made a bit better but manual overload for each works just fine.
	#
	# Could prob use a macro loop over entity and add overload if the repo type exists
	def repository(entity_class : Blog::Entities::User.class) : Blog::Entities::User::Repository

	require "crinja"

	ADI.configuration_annotation Blog::Annotations::Template, name : String

	@[ADI::Register]
	class HTMLFormatHandler
	include Athena::Framework::View::FormatHandlerInterface

	private CRINJA = Crinja.new loader: Crinja::Loader::FileSystemLoader.new "#{__DIR__}/../views"