Solidity – Is it Possible to Have a Mapping to a Tuple?

mappingsolidity

Is it possible to have a mapping where the values are a tuple?

mapping (address => (bool, uint)) participants;

Best Answer

If you use a struct, eg

struct Participant {
    bool value1;
    uint value2;
}

mapping (address => Participant) participants;

I don't think there's any way of using an actual Tuple eg var (a, b) in a mapping since the types of a and b cannot be declared with the syntax available. With a struct the types can be declared, which is necessary to declare the mapping type.

Related Solutions

[Ethereum] Is it possible to have enum as a mapping key type

That feature is not currently implemented. A simple workaround is to do

pragma solidity ^0.4.4;

 contract TestContract {
    enum TestEnum { ONE, TWO, THREE }
    mapping (bytes32 => uint) testMapping;

    function getValueOne() constant returns(uint) {
        return testMapping[sha3(TestEnum.ONE)];
    }

}

Just use the hash of the enum for the key instead of the actual enum item, and it will work fine.

solidity – Mapping Multiple Keys to a Single Struct

Yes, you would be making a copy.

What you could do instead is to just have an array of tests and then map addresses to array indices.

struct test{
    uint nonce;
    address friend;
}

mapping (address => uint) testMapping; //Maps addresses to index in `tests`
test[] tests;

Best Answer

Related Solutions

[Ethereum] Is it possible to have enum as a mapping key type

solidity – Mapping Multiple Keys to a Single Struct

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