fix parachain example

[Daanvdplas]

The parachain example was not working this fixes it (I took reference from the PolkadotConfig).

I wasn't able to fix the fact that it doesn't run the example from the root folder:
cargo run --bin parachain-example errors:

error: no bin target named parachain-example.

[tadeohepperle]

Looks good to me, I missed that, thanks for your PR. :)

[jsdw]

So previously, we used <SubstrateConfig as Config>::ExtrinsicParams, which resolves to SubstrateExtrinsicParams<SubstrateConfig>, which is DefaultExtrinsicParams<SubstrateConfig>.

With the change, we are using DefaultExtrinsicParams<PolkadotConfig> essentially. Which means that this whole StatemintConfig is now identical to PolkadotConfig.

I thought that the point of the difference was that Statemint used mostly polkadot config but one could tip using assetIDs (which used to be just a substrate config thing). Nowadays, both configs use thesame ExtrinsicParams.

I also wonder; does StateMint want tip asset IDs to be MultiLocations (which we currently don't support in Subxt but will soon, though one can write custom config to support this already).

@Daanvdplas what was not working that this fixed?
And if we want it to be correct, do we need to support MultiLocations in asset IDs too (I think so, but yeah we can do something about that later)?

[Daanvdplas]

Not sure what you mean with "tip".

The error I got:

In addition, in the README.md it says you can run this example by running:
cargo run --bin parachain-example

But this doesn't work. My PR doesn't include the solution for this. Only for running the example successfully.

[jsdw]

Aah ok, I see, thank you!

Since the config is actually identical to PolkadotConfig now, let's simplify first lines of this file to:

use subxt::{
    PolkadotConfig,
    utils::{AccountId32, MultiAddress},
    OnlineClient,
};
use subxt_signer::sr25519::dev::{self};

#[subxt::subxt(runtime_metadata_path = "statemint_metadata.scale")]
pub mod statemint {}

// PolkadotConfig or SubstrateConfig will suffice for this example at the moment,
// but PolkadotConfig is a little more correct, having the right `Address` type.
type StatemintConfig = PolkadotConfig;

#[tokio::main]
pub async fn main() {
 // ....
}

The cargo run --bin parachain-example works if you run it in the same folder as the README, which I think is a reasonably standard assumption, but we could be more explicit in the README about that :)

[Daanvdplas]

cargo run will work too then :). I thought it would be possible to run it from the root of the repo.

I will add your proposed changes!

[jsdw]

True; I guess at least the current command makes sure it won't work at all if ran from the wrong folder :D

[tadeohepperle]

@Daanvdplas Do you want to merge it into master? :)