Why does ethersjs not expose the contract address until deploy confirmation?

[kerzhner]

In theory, the contract address is known as soon as the deploy transaction is submitted.

[lalexgap]

This might be due to the fact that we're using generic transactions to deploy the contract. It looks like the Contract API might support this https://docs.ethers.io/ethers.js/html/api-contract.html#deployment

[tomclose]

You can get it with ethers - you just have to work a bit. This is how ethers does it itself:

deploy(...args: Array<any>): Promise<Contract> {

  // Get the deployment transaction (with optional overrides)
  let tx = this.getDeployTransaction(...args);

  // Send the deployment transaction
  return this.signer.sendTransaction(tx).then((tx) => {
    const contract = new Contract(getContractAddress(tx), this.interface, this.signer);
    defineReadOnly(contract, 'deployTransaction', tx);
    return contract;
  });,
};

which uses this method from utils:

// http://ethereum.stackexchange.com/questions/760/how-is-the-address-of-an-ethereum-contract-computed
export function getContractAddress(transaction: { from: string, nonce: Arrayish | BigNumber | number }) {
    if (!transaction.from) { throw new Error('missing from address'); }
    var nonce = transaction.nonce;

    return getAddress('0x' + keccak256(encode([
        getAddress(transaction.from),
        stripZeros(hexlify(nonce))
    ])).substring(26));
}

We should be able to do the same in the transaction-sender.