Is it possible to make DSL in crystal?

[Grabli66 None]

Hi. I am trying to make some DLS in Crystal like this:

class Item2
  def initialize(&blk)
    instance_eval(&blk)
  end 
 
  def item2(&blk)
    Item2.new(&blk)
  end
 
  def test(s)
    puts "test"
  end
end

class Item1
  def initialize(&blk)
    instance_eval(&blk)
  end 
 
  def item2(&blk)
    Item2.new(&blk)
  end
end

def item1(&blk)
  Item1.new(&blk)
end

item1 {
  item2 {
    test("test")
  }
}

It works in Ruby. But Crystal compiler says that variable or method "item2" is undefined.
Where i am wrong?

[Jonne Haß]

There's no instance_eval. There's a limited replacement though, with x yield. See http://carc.in/#/r/e2p

Another and probably greater avenue for building DSLs in Crystal is its macro system, three examples taking it quite far are artanis: https://github.com/ysbaddaden/artanis, the spec DSL of minitest.cr: https://github.com/ysbaddaden/minitest.cr/blob/master/src/minitest/spec.cr and spec2: https://github.com/waterlink/spec2.cr

Have fun!

- Jonne

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[Grabli66 None]

Greate thanks.