uint256 doesn't work as array index

[scherrey]

Version Information

• vyper Version (output of vyper --version): 0.1.0b10
• OS: linux Kubuntu 14.04 Linux satriani 4.9.119-first-custom lay an egg #1 SMP Mon Aug 13 18:33:19 +07 2018 x86_64 x86_64 x86_64 GNU/Linux
• Python Version (output of python --version): 3.6.3
• Environment (output of pip freeze):
  asn1crypto==0.24.0
  async-generator==1.10
  async-lru==0.1.0
  asyncio-cancel-token==0.1.0a2
  atomicwrites==1.3.0
  attrdict==2.0.1
  attrs==19.1.0
  backcall==0.1.0
  base58==1.0.3
  bloom-filter==1.3
  cached-property==1.5.1
  cachetools==3.1.1
  certifi==2019.3.9
  cffi==1.12.3
  chardet==3.0.4
  coincurve==10.0.0
  cryptography==2.7
  cypari==2.3.0
  cytoolz==0.9.0.1
  decorator==4.4.0
  eth-abi==2.0.0b9
  eth-account==0.4.0
  eth-bloom==1.0.3
  eth-hash==0.2.0
  eth-keyfile==0.5.1
  eth-keys==0.2.4
  eth-rlp==0.1.2
  eth-tester==0.1.0b39
  eth-typing==2.1.0
  eth-utils==1.6.1
  ethpm==0.1.4a19
  future==0.17.1
  FXrays==1.3.3
  hexbytes==0.2.0
  idna==2.8
  ifaddr==0.1.6
  importlib-metadata==0.18
  ipdb==0.12
  ipfshttpclient==0.4.12
  ipython==7.5.0
  ipython-genutils==0.2.0
  jedi==0.13.3
  jsonschema==2.6.0
  lahja==0.12.0
  lru-dict==1.1.6
  lxml==4.3.3
  more-itertools==7.0.0
  multiaddr==0.0.8
  mypy-extensions==0.4.1
  netaddr==0.7.19
  netdisco==2.6.0
  networkx==2.3
  packaging==19.0
  parsimonious==0.8.1
  parso==0.4.0
  pexpect==4.7.0
  pickleshare==0.7.5
  pipenv==2018.11.26
  plink==2.2
  pluggy==0.12.0
  plyvel==1.0.5
  prompt-toolkit==2.0.9
  protobuf==3.8.0
  ptyprocess==0.6.0
  py==1.8.0
  py-ecc==1.7.0
  py-evm==0.2.0a42
  py-geth==2.1.0
  pycparser==2.19
  pycryptodome==3.8.2
  pyethash==0.1.27
  Pygments==2.4.2
  pyparsing==2.4.0
  pypng==0.0.19
  pyrsistent==0.15.2
  pysha3==1.0.2
  pytest==4.6.3
  pytest-ethereum==0.1.3a6
  python-dateutil==2.8.0
  requests==2.22.0
  rlp==1.1.0
  semantic-version==2.6.0
  simplegeneric==0.8.1
  six==1.12.0
  snappy-manifolds==1.0
  spherogram==1.8.1
  SQLAlchemy==1.3.4
  toolz==0.9.0
  traitlets==4.3.2
  trie==1.4.0
  typing-extensions==3.7.2
  uPnPClient==0.0.8
  urllib3==1.25.3
  uvloop==0.11.2
  varint==1.0.2
  virtualenv==16.6.0
  virtualenv-clone==0.5.3
  vyper==0.1.0b10
  wcwidth==0.1.7
  web3==5.0.0b2
  websockets==7.0
  zeroconf==0.22.0
  zipp==0.5.1

What's your issue about?

Attempts to use uint256 as an index parameter into an array results in the following error:

vyper.exceptions.TypeMismatchException: line 207:8 Typecasting from base type uint256 to int128 unavailable

Example code:

MAX_AUCTION_ITEMS: constant(uint256)  = 5

tokenIds: uint256[MAX_AUCTION_ITEMS]
tokenQty: uint256 # Total number of tokenIds actually in the tokenIds list.



@public
def __init__(_token_ids: uint256[MAX_AUCTION_ITEMS], _kyc_provider: address, _start: timestamp, _end: timestamp):
    """
    _token_ids - a list of each UNIQUE tokenId in order of most valuable
    being the first in the list.

    _kyc_provider - wallet address of the account with rights to manage
    the approved bidder list.

    _start - the datetime when the auction can accept bids.

    _end - the datetime when the auction ends normal bidding activities.
    """

    # load up the tokenIds
    for tokenId in _token_ids:
        if tokenId == 0: break


        self.tokenIds[self.tokenQty] = tokenId ### vyper.exceptions.TypeMismatchException: line 207:8 Typecasting from base type uint256 to int128 unavailable

        
        self.tokenQty += 1    

How can it be fixed?

@charles-cooper figured out that the following work around get's us by:

self.tokenIds[convert(self.tokenQty, int128)] = tokenId