How to identify the calling function from within a modifier?

Question

Two Solidity functions foo and bar both calling modifier m which emits an event Called with a unique identifier for the calling function. It could be any identifier, but it has to be unique per contract.

The modifier m can’t be called with more arguments as part of the requirements.

contract MyContract {
    event Called(bytes functionID);

    function foo() private m {
        // ...
    }

    function bar() private m  {
        // ...
    }

    modifier m {
        emit Called( /*  TODO: unique identifier for "calling" function, ie. foo or bar */  );
        _;
    }
}

How can I identify the calling function from within the modifier?

Answer 1

You could try passing args to the modifier

contract MyContract {
    event Called(bytes functionID);

    function foo() private m('foo') {
        // ...
    }

    function bar() private m('bar')  {
        // ...
    }

    modifier m(string func) {
        emit Called(func);
        _;
    }
}

Hope it helps