# Note for reviewer
Most changes are just syntax changes necessary for the new version.
Most important files should be the ones under the `xcm` folder.
# Description
Added XCMv4.
## Removed `Multi` prefix
The following types have been renamed:
- MultiLocation -> Location
- MultiAsset -> Asset
- MultiAssets -> Assets
- InteriorMultiLocation -> InteriorLocation
- MultiAssetFilter -> AssetFilter
- VersionedMultiAsset -> VersionedAsset
- WildMultiAsset -> WildAsset
- VersionedMultiLocation -> VersionedLocation
In order to fix a name conflict, the `Assets` in `xcm-executor` were
renamed to `HoldingAssets`, as they represent assets in holding.
## Removed `Abstract` asset id
It was not being used anywhere and this simplifies the code.
Now assets are just constructed as follows:
```rust
let asset: Asset = (AssetId(Location::new(1, Here)), 100u128).into();
```
No need for specifying `Concrete` anymore.
## Outcome is now a named fields struct
Instead of
```rust
pub enum Outcome {
Complete(Weight),
Incomplete(Weight, Error),
Error(Error),
}
```
we now have
```rust
pub enum Outcome {
Complete { used: Weight },
Incomplete { used: Weight, error: Error },
Error { error: Error },
}
```
## Added Reanchorable trait
Now both locations and assets implement this trait, making it easier to
reanchor both.
## New syntax for building locations and junctions
Now junctions are built using the following methods:
```rust
let location = Location {
parents: 1,
interior: [Parachain(1000), PalletInstance(50), GeneralIndex(1984)].into()
};
```
or
```rust
let location = Location::new(1, [Parachain(1000), PalletInstance(50), GeneralIndex(1984)]);
```
And they are matched like so:
```rust
match location.unpack() {
(1, [Parachain(id)]) => ...
(0, Here) => ...,
(1, [_]) => ...,
}
```
This syntax is mandatory in v4, and has been also implemented for v2 and
v3 for easier migration.
This was needed to make all sizes smaller.
# TODO
- [x] Scaffold v4
- [x] Port github.com/paritytech/polkadot/pull/7236
- [x] Remove `Multi` prefix
- [x] Remove `Abstract` asset id
---------
Co-authored-by: command-bot <>
Co-authored-by: Keith Yeung <kungfukeith11@gmail.com>
Contracts 📝
This is a parachain node for smart contracts; it contains a default configuration of
Substrate's module for smart contracts ‒ the pallet-contracts.
The node is only available on Rococo, a testnet for Polkadot and Kusama parachains.
It has been configured as a common good parachain, as such it uses the Rococo relay
chain's native token ROC instead of defining a token of its own.
See the section Rococo Deployment below for more details.
If you have any questions, it's best to ask in the Substrate StackExchange.
Smart Contracts Development
This node contains Substrate's smart contracts module ‒ the
pallet-contracts.
This pallet takes smart contracts as WebAssembly blobs and defines an API
for everything a smart contract needs (storage access, …).
As long as a programming language compiles to WebAssembly and there exists an implementation
of this API in it, you can write a smart contract for this pallet (and thus for this parachain)
in that language.
This is a list of languages you can currently choose from:
- Parity's ink! for Rust.
- ask! for Assembly Script.
- The Solang compiler for Solidity.
There are also different user interfaces and command-line tools you can use to deploy or interact with contracts:
- Contracts UI ‒ a beginner-friendly UI for smart contract developers.
polkadot-js‒ the go-to expert UI for smart contract developers.cargo-contract‒ a CLI tool, ideal for scripting or your terminal workflow.
If you are looking for a quickstart, we can recommend ink!'s Guided Tutorial for Beginners.
Build & Launch a Node
To run a Contracts node that connects to Rococo
you will need to compile the polkadot-parachain binary:
cargo build --release --locked --bin polkadot-parachain
Once the executable is built, launch the parachain node via:
./target/release/polkadot-parachain --chain contracts-rococo
Refer to the setup instructions to run a local network for development.
Rococo Deployment
We have a live deployment on Rococo ‒ a testnet for Polkadot and Kusama parachains.
You can interact with the network through Polkadot JS Apps, click here for a direct link to the parachain.
This parachain uses the Rococo relay chain's native token ROC instead of defining a token of its own.
Due to this you'll need ROC in order to deploy contracts on this parachain.
As a first step, you should create an account. See here for a detailed guide.
As a second step, you have to get ROC testnet tokens through the Rococo Faucet.
This is a chat room in which you'd need to post the following message:
!drip YOUR_SS_58_ADDRESS:1002
The number 1002 is the id of this parachain on Rococo, by supplying it the faucet will teleport ROC
tokens directly to your account on the parachain.
If everything worked out, the teleported ROC tokens will show up under
the "Accounts" tab.
Once you have ROC you can deploy a contract as you would normally.
If you're unsure about this, our guided tutorial
will clarify that for you in no time.