Whats the point of modifiers? [duplicate]

Question

So let's assume the following code:

modifier Owner() {
    if (msg.sender == owner) _; 
}
function uploadContent() external Owner {

   uploadContent() ..
}

Why not use this?

function checkOwner() internal {
   require(msg.sener == owner, "Youre not the owner");
}

function uploadContent() external Owner {
     checkOwner()
     uploadContent() ...
}

Whats the difference? Is it cheaper in terms of gas cost? Because I dont see any reason why to use the first approach?

Answer 1

A modifier can do stuff at the start and at the end and share a variable

A real world example from 1inch contract

modifier discountGST {
    uint256 gasStart = gasleft();

    _;

    uint256 gasSpent = 21000 + gasStart - gasleft() + 16 * msg.data.length;
    gst.freeFromUpTo(msg.sender, (gasSpent + 14154) / 41130);
}

It can be implemented with a function but it will not be as elegant as using a modifier. If you have to repeat it for several times it will be worse.

I agree with you that some uses it doesn't improve code clarity (using it for requires) and sometimes it can add complexity (multiple inheritance and hierarchies).