Fetching stored values for use in function logic

Question

Are there any benefits from fetching stored data into other functions by calling a function to call a private variable, instead of calling the private variable directly? What is best practices?

example

 contract PlayerExample {

    uint private maximumPlayers

    uint private players;

    function playersCount() public view returns (uint) {
        return players;
    }

    function playerSlotsLeft() public view returns (uint) {
        return (maximumPlayers - players);
        //or is it better to do 
        //return (maximumPlayers - playersCount());
    }
 }

Answer 1

From a gas perspective - specifically, if this were ever being called by another contract as part of a transaction, rather than just a call being made directly - then not having another function call on the stack is going to be cheaper:

pragma solidity ^0.5.1; 

contract PlayerExample {
    uint private maximumPlayers = 10;
    uint private players = 5;

    function playerSlotsLeft() public view returns (uint) {
        return (maximumPlayers - players);
    }
}

• Transaction cost: 21874
• Execution cost: 602

---

pragma solidity ^0.5.1; 

contract PlayerExample {
    uint private maximumPlayers = 10;
    uint private players = 5;

    function playersCount() public view returns (uint) {
        return players;
    }

    function playerSlotsLeft() public view returns (uint) {
        return (maximumPlayers - playersCount());
    }
}

• Transaction cost: 21931
• Execution cost: 659

Answer 2

If you use a function you have the possibility to add extra functionality to it when needed, for example access checks. Otherwise I don't see much benefits in using a function.