Access to constants through contract names

[ethernomad]

It is currently possible to do this:

pragma solidity ^0.4.3;

contract Constants {

    uint constant FLAG = 0x1;
}

contract Test is Constants {

    function x() returns (uint) {
        return Constants.FLAG;
    }
}

But surely it should be possible to do this:

pragma solidity ^0.4.3;

contract Constants {

    uint constant FLAG = 0x1;
}

contract Test {

    function x() returns (uint) {
        return Constants.FLAG;
    }
}

[chriseth]

We still have to figure out how we want constants to behave exactly. Currently, I think you might be able to access private information via constants, which is perhaps not such a good idea.

[chriseth]

Now that we have the pure check, it should be fine to do this at least for actually pure constants.

[j-h-scheufen]

As a side note to this ticket: To simulate the desired constant behavior until it's fully supported in the language I'm using a workaround via libraries:

library Constants {
   function FLAG() pure returns (uint) {
      return 0x1;
   }
}

contract Test {
    function x() returns (uint) {
        return Constants.FLAG();
    }
}

To be frank, I actually don't know the cost of simulating constants via library functions, because you have an additional function on the callstack and memory every time you access it, but it does the trick and gives me what I need for more efficient coding. Once constants are supported fully, it is not too hard to turn the library into a contract and search/replace its usage to remove the () parentheses.

I'm not worried about gas cost as the solutions that use this approach run on a permissioned EVM with no gas limit, but it would be great to get your opinion on the above, @chriseth.