Cannot return ERC20 token address from contract

[Pet3ris]

Hi There,

I'm trying to compile the following contract running master:

Input contract

from vyper.interfaces import ERC20

token: ERC20

@public
@constant
def tokenAddress() -> address:
    return self.token

Output

vyper.exceptions.TypeMismatchException: line 8: Trying to return base type address(ERC20), output expecting address
    return self.token
-----------^

I can fix it temporarily by changing the address to an address(ERC20), this compiles to runtime bytecode, but doesn't compile when extracting the ABI:

Input contract 2 (-f abi)

from vyper.interfaces import ERC20

token: ERC20

@public
@constant
def tokenAddress() -> address(ERC20):
    return self.token

Output

vyper.exceptions.InvalidTypeException: line 7: Invalid base unit
def tokenAddress() -> address(ERC20):
------------------------------^

[jacqueswww]

OK let me think of a few other uses cases, and I'll wrap those all in one PR (I think we are missing a few cases in the test suite).

[Pet3ris]

@jacqueswww - thanks a lot, may I selfishly suggest elements of the Uniswap contract for different ways of integrating ERC20 tokens as it has its own as well as external :).

[jacqueswww]

Once I have assembled the PR, let's test it against uniswap before merging it ;)