Is a constructor needed to set a contract owner?

Question

until now I have set the owner in a contract like so:

pragma solidity ^0.5.2;

contract SampleContract{

     address payable owner = msg.sender;

}

in the docs it is suggested to do it this way:

pragma solidity ^0.5.2;

contract SampleContract{

     address payable owner;

     constructor() public {
         owner = msg.sender;
     }

}

I don't notice any difference in the behavior of the contract. Are both ways equivalent or is there a possible security issue with the first one?

Thanks a lot

Answer 1

No, at the moment both of them work properly.

You can even write something like:

address payable owner = 0xfea...0e1;

when you know who should be the owner before deployment... that is absolutely normal.

In theory using the hard coded version, both with the msg.sender or the 0x... versions, someone (an optimizer?) should try to be convinced that they are constant elements and not variables, but at the moment the solidity compiler seems not so worried about that.

Answer 2

No you are fine. A constructor is a function that gets called only once when the contract launches. Both produce the same results.

Answer 3

Although it sounds like it might imply special status, owner is merely an address. Nothing more. Nothing special.

It only receives "special" status when the contract is coded as such. For example:

modifier onlyOwner {
  require(msg.sender == owner);
  _;
}

function sensitiveRestrictedFunction() public onlyOwner ...

You can even set it to something new:

function changeOwner(address newOwner) public onlyOwner ...
  require(newOwner != address(0));
  owner = newOwner;
}

Hope it helps.