[Ethereum] How to refer to a contract own address inside it

Alright. Now. Your events should be logged in solidity but you have to call the event in JS to access the logged information. There's a whole section on these things in the web3 api. https://github.com/ethereum/wiki/wiki/JavaScript-API#contract-events

Here's a sketch of a way to do it, but be warned this isn't for the faint of heart.

1. Create a base contract with a global variable that will point to the current library.
2. Create the contract (the host) inheriting from the base contract. Also create the first real library for it.
3. Create a library (the proxy) inheriting from the base contract. (This will allow it to read the host contract's variable) This library should only have a fallback function, which immediately uses delegatecall to send the calldata to the current library.
4. Deploy all the contracts, linking the proxy to the host contract. Solidity won't know that the proxy library doesn't actually implement the actual library's interface--all it sees is the address.
5. When you want to upgrade the library, just change the global variable in the host contract.

As I warned, this is not for the faint of heart. You'll probably bash your head against all kinds of walls, desks, and miscellaneous hard surfaces getting this all to work. Then you might calculate the effort involved in this, as opposed to just redeploying the contracts in the first place. Unless you really, really don't want to redeploy the contracts, you'd probably be better off just doing that.