Learning the network's gas token address?

[doughertym]

Hello,

I am not sure this is a course-specific-question, but googling (actually presearching) has not resulted in success, so I thought I would just give it a try here as a next step.

Question: Can I get the current network's gas token from within the contract itself? Or do I have to get the token externally and pass it into the contract myself?

The scenario is that suppose my contract does some work on behalf of the caller and, as a result of that work it should charge the caller a small fee. So given the function:

import "@openzeppelin/contracts/token/ERC20/ERC20.sol";
contract Foo {
  ERC20 private immutable networkToken;

  function doSomething() public payable {
     // do some cool thing...
    networkToken.transferFrom(msg.sender, this, feeAmount);
  }
}

If the contract is deployed to Ethereum networkToken should be ETH, on Avalanche it should be AVAX, Polygon MATIC, etc.

Thanks, in advance, for your help.

[PatrickAlphaC]

So the network token isn't an ERC20, it's the native value and will automatically use that. To send value, we'd do something like:

contract Foo {

  function doSomething() public payable {
     // do some cool thing...
         (bool success, ) = i_owner.call{value: address(this).balance}("");
        require(success);
  }
}

[doughertym]

Thanks @PatrickAlphaC. I guess I was over-thinking the problem. Nice and simple solution. Thanks!