Solidity Interfaces – Difference Between ERC20.transferFrom and IERC20.transferFrom Explained

erc-20interfacessolidity

Calling ether of these in my contract does the same thing. What is the difference then?

ERC20(tokenAddress).transferFrom(msg.sender, address(this), amount);

IERC20(tokenAddress).transferFrom(msg.sender, address(this), amount);

I thought IERC20 was just the interface so I would have to implement the function myself. But both transfer the token between addresses.

Could I have a caching problem, or do they actually do the same thing?

Best Answer

They're effective the same thing in this case.

But what ERC20 does that's different from IERC20 is that it's importing the entire contract API, as opposed to the public bits.

When you're using IERC20, there's zero chance you'll accidentally tie into custom functionality. That's why it's better. you're aiming for a smaller interface, so it keeps the design cleaner.

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[Ethereum] ERC20 tokens approve and transferFrom

The ERC20 has been accepted as a standard, wallets and explorer will use that specification as a base to implement their functionality.

It is not perfect but it is widely used. IMHO it is better to be compatible with most applications. It is within the standard to return false for those methods that return a bool with the result of the operation, or zero for allowance.

Solidity CALL – Difference Between Direct Call and Creating Contract Object

There's a huge difference between them

function createFoo (address _contractAddress){
    Contract A = A(_contractAddress);
    A.foo();
}

If foo() fails the call to createFoo() will also fail and it will propagate reversing any change you have made.

Another difference is you can retrieve the value returned by foo(). If the function returned an address you can assign to a variable.

address who = A.foo();

In the second case if foo() fails, call will return false. But it will not reverse changes you have made, you have to explicitely call revert().

function callFoo (address _contractAddress) {
    address newAddress = _contractAddress;
    newAddress.call(bytes4(sha3("foo()")));
}

And you do not have access to the value returned by foo(), call only return true if it executed successfully or false if it has failed.

Best Answer

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Solidity CALL – Difference Between Direct Call and Creating Contract Object

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