Question about the design of ERC20 transferFrom function

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1

In the OpenZeppelin ERC20 contract, the code is written in such a way that user must manually approve spenders to spend their tokens on the user's behalf.

This allowance is then checked when a transfer is made:

    function transferFrom(
        address from,
        address to,
        uint256 amount
    ) public virtual override returns (bool) {
        address spender = _msgSender();
        _spendAllowance(from, spender, amount);
        _transfer(from, to, amount);
        return true;
    }

However, the way it's currently written requires the user to approve themselves if they want to transfer their own tokens. Why is it written this way? Wouldn't a simple check for from == spender and then skipping _spendAllowance suffice?

2

Hey @greentriangles1
why a user should use transferFrom instead of transfer to send tokens by his own?

transferFrom usually is necessary only if it is called by someone different from the owner

3

Sure, transfer makes more sense, but the same logic still occurs

4

Are you sure? Please show where

5

User or EOA can directly call transfer() to transfer funds.
Approve and transferFrom are required when a smart contract needs to transfer funds on behalf of user.

6

There may be some confusion here because for ERC721 and ERC1155 all transfers are done through transferFrom, including user-initiated transfers. In ERC20 they are separate: transfer and transferFrom.

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