A JS style console.log() function for solidity.

console.sol

pragma solidity ^0.4.10;

// Update: Just use HardHat's: https://github.com/nomiclabs/hardhat/blob/master/packages/hardhat-core/console.sol

// Enables event logging of the format `console.log('descriptive string', variable)`, 
// without having to worry about the variable type (as long as an event has been declared for that type in the 
// Console contract.

contract Console {
    event LogUint(string, uint);
    function log(string s , uint x) {
        LogUint(s, x);
    }
    
    event LogInt(string, int);
    function log(string s , int x) {
        LogInt(s, x);
    }
    
    event LogBytes(string, bytes);
    function log(string s , bytes x) {
        LogBytes(s, x);
    }
    
    event LogBytes32(string, bytes32);
    function log(string s , bytes32 x) {
        LogBytes32(s, x);
    }

    event LogAddress(string, address);
    function log(string s , address x) {
        LogAddress(s, x);
    }

    event LogBool(string, bool);
    function log(string s , bool x) {
        LogBool(s, x);
    }
}

contract NeedsDebugging is Console {
    
    function InspectMePlease(){
        log("name", uint(1));
    }
}

Just great.!

2021 version!

contract Console {
    event LogUint(string, uint256);

    function log(string memory s, uint256 x) public {
        emit LogUint(s, x);
    }

    event LogInt(string, int256);

    function log(string memory s, int256 x) public {
        emit LogInt(s, x);
    }

    event LogBytes(string, bytes);

    function log(string memory s, bytes memory x) public {
        emit LogBytes(s, x);
    }

    event LogBytes32(string, bytes32);

    function log(string memory s, bytes32 x) public {
        emit LogBytes32(s, x);
    }

    event LogAddress(string, address);

    function log(string memory s, address x) public {
        emit LogAddress(s, x);
    }

    event LogBool(string, bool);

    function log(string memory s, bool x) public {
        emit LogBool(s, x);
    }

    event LogString(string);

    function log(string memory s) public {
        emit LogString(s);
    }
}

Oh, just use Hardhat now:https://github.com/nomiclabs/hardhat/blob/master/packages/hardhat-core/console.sol

+1 https://github.com/NomicFoundation/hardhat/blob/master/packages/hardhat-core/console.sol