Dynamically call event with arugments

Question

How do I dynamically call an event with a name? For example, my contract has a few events and based on some conditions I would like to call one of them. I don't want to use a switch or an if statement but would like to specify the name of the event and call it with data

I tried the following simple example but it didn't work.

event StoredValue(
   string data);

function callEvent(string eventName, data) {
this.call(bytes4(sha3("StoredValue(data)")));
}

I want to pass a name and arguments into a function which will be used to call the event

Answer 1

Events aren't functions, so you'll have to wrap them in functions to accomplish this and instead pass the function name in, e.g:

modifier onlySelf(){
    require(msg.sender==this);
    _;
}

event EventOne(string data);
event EventTwo(string data);

function logEventOne(string data) public onlySelf{
    EventOne(data);
}

function logEventTwo(string data) public onlySelf{
    EventTwo(data);
}

function callEvent(string functionSignature, string data){
    this.call(bytes4(sha3(functionSignature)),data);
}

Note that, since this.call will create a message call, the functions you call must be public to work. To get around the fact that they're public, I added the onlySelf modifier so only the contract can call them.

I would advise against doing any of this since events must exist at compile time anyway, so you can just do EventOne/EventTwo directly instead of dynamically.