add convenience method for checking if a contract is deployed

const someContract = new ethers.Contract( ... )
const isDeployed = await someContract.isDeployed()

if (!isDeployed) {
   // deploy it
}

// continue

[ricmoo]

I don’t really see much value in an .isContract method, since it is literally just doing ((await provider.getCode(address)) === "0x"). It seems simple enough and I could imagine someone expecting the call to verify the bytecode matches the contract bytecode, which a contract doesn’t have. I have considered a similar thing for the contract factory, but it is not reliable, since the initcode is what the Factory has, not the runtime, and since the initcode is executed there is no way to verify that it is correct (see halting problem 😉).

So, I would think in many cases people would care about what the bytecode is, not that it simple exists and otherwise it is a very simple call to do yourself. The vast majority of use-cases does not need to check either, since the a contract is generally long-lived and deployed long before interacting with it, especially customers.

If this is for testing, the ContractFactory adds the .deployTrasaction on the Contract, so it is easy to await contract.deployTransaction.wait(), which also throws if the contract failed to deploy. So, it should almost never be the case you have a contract connected to an unknown-to-be-deployed contract, unless you have tests running across multiple processes, which sounds painful… 😒

If you are looking for deterministic deployments though, you might be interested in rooted or wisps.

Does that all make sense?

[garyng2000]

@ricmoo, I do have usage scenario where the deployment of the contract are completely separated from where it is used(say multi-node scale out situation), thus the .wait().then() style is rarely used. So logical .isContract(someAddress) of some form is used a lot. Though I am with you that a thin wrapper of .getCode() is probably not worth to be added as a generic library feature. It can be easily implemented via HOF or mixin for those who prefers it.