Function approve

wasmtest/contracts-cplus/test_oep4.py:196–219

owner allow spender to spend amount of token from owner account Note here, the amount should be less than the balance of owner right now. :param owner: :param spender: :param amount: amount>=0 :return: True means success, False or raising exception means failure.

(owner,spender,amount)

def approve(owner,spender,amount):
    """
    owner allow spender to spend amount of token from owner account
    Note here, the amount should be less than the balance of owner right now.
    :param owner:
    :param spender:
    :param amount: amount>=0
    :return: True means success, False or raising exception means failure.
    """
    if len(spender) != 20 or len(owner) != 20:
        raise Exception("address length error")
    if CheckWitness(owner) == False:
        return False
    if amount > balanceOf(owner) or amount < 0:
        return False

    key = concat(concat(APPROVE_PREFIX,owner),spender)
    Put(ctx, key, amount)

    # Notify(["approval", AddressToBase58(owner), AddressToBase58(spender), amount])
    # ApprovalEvent(AddressToBase58(owner), AddressToBase58(spender), amount)
    ApprovalEvent(owner, spender, amount)

    return True


def transferFrom(spender,from_acct,to_acct,amount):