New standard: Coin Receiver

[damip]

Context

In Massa we allow native coin transfers (transfer_coins):

• from:
  • any User account on which the current context has write access
  • any Smart Contract account on which the current context has write access
• towards:
  • any User account
  • any Smart Contract account on which the current context has write access

Not allowing foreign Smart Contract accounts to receive native tokens without going through the coins parameter of call is deliberate: it allows Smart Contracts to filter and refuse incoming coin transfers.

This document defines an interface that is exposed by all Smart Contract accounts that need to receive native coins.

User flow

To transfer native coins towards a foreign Smart Contract account, one can call the coin reception function that account exposes if it implements this proposal. If the Smart Contract does not implement this proposal, it means that it is not meant to receive native coins directly.

Technical details

Prefix to all exposed methods: cr1 ("Coin Receiver V1")

Expose a single, parameter-less function named cr1_receive_coins that does not return anything.

QA testing

Try sending coins to a Smart Contract implementing this.