FA2.1 as extension of the FA2 standard - DRAFT

[Jordan]

At SmartPy we’ve read the proposal and wrote a contract with some tests that implements it.

The contract is here: FA2_nft_minimal.py.

I encourage people to read it if they want to understand how the standard is supposed to work. Please tell us if there is any mistake.

Our remarks are:

• Overall it’s a good and interesting proposal.
• We are waiting for the merge of the TZIP proposal.
• The approve entrypoint explanations need to be a bit more explicit:

  • Indicate that the transfer fails if the approve falls under zero.

  • Explicit the error message. We have 3 suggestions:

    1. Keep "FA2_NOT_OPERATOR" to be fully compatible with FA2
    2. "FA2_INSUFFICIENT_ALLOWANCE"
    3. Mix 1) and 2) and fails with a pair of "FA2_NOT_OPERATOR" and "FA2_INSUFFICIENT_ALLOWANCE". We can even give the allowance in the error message.

  • Clarify what to do if the allowance equals 0 with a transfer of 0 tokens?
    I suggest to pass because it permits to test the allowance system.
    To be clear, a transfer of 0 tokens with:

    1. no allowance => fail (so the system remains compatible with FA2)
    2. allowance of 0 => pass

    In this case the allowance should not be removed if a transfer, and export_ticket or anything that reduces the allowance to zero. It must be zero.
    We are open to alternatives.