Can I have a listener to cryptocurrencies / tokens reaching a specific address?

Question

Let's say that there is an address called 0x1

There is another address called 0x2 which just released a new token called ABA. Is there a way to constantly listen for 0x1 to see if it receives ABA from any users, without making the user interacting with your smart contract? In other words, if the users sends their ABA to 0x1, they will receive ABAv2 in exchange, depending on the amount they sent to 0x1. The user would be able to select in their smart contract the address they want to send to, in this case 0x1 and everytime they make a transaction to 0x1 they "automatically interract" with the specified logic.

Hope that makes sense.

The tokens I'm talking about are ERC20s.

Answer 1

You can listen for events in the ABA contract and filter for the destination address you are interested in.

This is a client-side (includes servers) opportunity only because contracts cannot (easily) listen to event logs.

Hope it helps.