CODEWITHSUNDEEP
crystal-lang
Alex Craft
Alex Craft

Reputation: 15336

Why JSON::Builder not using `with obj yield` modifier?

Crystal allows to use with keyword to improve DSL.

But in its standard library it's not used for JSON::Builder, the example from docs looks like that:

JSON.build do |json|
  json.object do
    json.field "name", "foo"
  end
end

While it could be written shorter as:

JSON.build do
  object do
    field "name", "foo"
  end
end

So, why it's not implemented in such way? Are there any drawbacks of using with xxx yield?

Possible implementation

class JSON
  def self.build
    with JSON.new yield
  end

  def object
    builder = JSONObject.new
    with builder yield self
    p builder.result
  end

  class JSONObject
    getter :result
    @result = Hash(String, String).new
    def field(key : String, value : String)
      @result[key] = value
    end
  end
end

Upvotes: 1

Views: 66

Answers (1)

asterite
asterite

Reputation: 2926

Because in many cases you want to pass a builder to another method, and there's no way to refer to self inside with ... yield.

Additionally, JSON::Builder isn't used that frequently so it's not a big difference to have to write a few more characters now and then.

Upvotes: 2

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