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Chapter 3: Advanced

Lesson 2: Parameters for new users

When users will call the register_user transition, they'll have to provide some data to the transition so that they could be uniquely registered. We’ll ask the users to provide:

  • Their twitter id
  • Their wallet id

    • We have covered this in the first chapter but for a quick reference, in case we want to declare multiple parameters for a transition, then we can do so by separating the parameter names and types by commas, as shown below:

    We have a task for you!

    In the bracket after the transitionregister_user declare two variables:

  • Declare variable user_address of the type ByStr20. This will hold the wallet address of the user.

  • Declare variable twitter_username of the type String. This will hold the twitter id of the user.

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    Solution
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    scilla_version 0
    import BoolUtils
    library SocialMediaPayment
    let one_msg = 
      fun (msg: Message) => 
      let nil_msg = Nil {Message} in
      Cons {Message} msg nil_msg
    let zero = Uint128 0
    let not_owner_code = Uint32 1
    let accepted_code = Uint32 0
    contract SocialMediaPayment (owner: ByStr20)
    transition deposit()
      sender_is_owner = builtin eq _sender owner;
      match sender_is_owner with
      | False =>
        msg = { _tag: "";
                _recipient: _sender;
                _amount: zero;
                code: not_owner_code};
        msgs = one_msg msg;
        send msgs
      | True =>
        accept;
        msg = { _tag: "";
                _recipient: _sender;
                _amount: zero;
                code: accepted_code};
        msgs = one_msg msg;
        send msgs
      end
    end
    (*type within  the brackets in the line below *)
    transition register_user (user_address: ByStr20, twitter_username: String)
    end
    scilla_version 0
import BoolUtils

library SocialMediaPayment

let one_msg = 
  fun (msg: Message) => 
  let nil_msg = Nil {Message} in
  Cons {Message} msg nil_msg

let zero = Uint128 0
let not_owner_code = Uint32 1
let accepted_code = Uint32 0


contract SocialMediaPayment (owner: ByStr20)

transition deposit()
  sender_is_owner = builtin eq _sender owner;
  match sender_is_owner with
  | False =>

    msg = { _tag: "";
            _recipient: _sender;
            _amount: zero;
            code: not_owner_code};
    msgs = one_msg msg;
    send msgs

  | True =>
    accept;
    msg = { _tag: "";
            _recipient: _sender;
            _amount: zero;
            code: accepted_code};
    msgs = one_msg msg;
    send msgs

  end
end

(*type within  the brackets in the line below *)
transition register_user ()


end
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    Chapter 3: Advanced

    Lesson 1: Registering users

    Chapter 3: Advanced

    Lesson 3: Map – Declaration