Is it possible to make multiple function calls in a single transaction?

Question

Say I want to make a transaction that calls foo() and the calls bar() afterwards. I could make a contract that calls them both in sequence, but that's kind of a pain. Is there a way to just call both without prompting the user for multiple signatures? And if so will foo() revert if bar() reverts and vice versa?

Answer 1

There is no way to do this without using a contract.

In general, due to Ethereum's "no features" design principle, anything more complex than a simple transaction will require a smart contract. In this case the contract would be very small, and you can simply deploy it once and reuse it.

Answer 2

You may call all in one transaction by deploying contract looking like this:

contract Target {
    function foo () public;
    function bar () public;
}

contract Batch {
  constructor (Target target) public {
    target.foo ();
    target.bar ();
    selfdestruct (msg.sender);
  }
}

This will revert foo() in case bar() will fail.

Though, this will call foo() and bar() from temporary smart contract address rather than from your real address.

Answer 3

The user signs one transaction. It can involve many contracts and functions, according to design. It will also be atomic - completing or reverting entirely.

There is no way to have the user sign two such transactions or receive the same assurances about two separately signed transactions.

Hope it helps.