Improve readme and decode sub-command documentation

CHANGELOG.md

@@ -8,6 +8,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Changed
 - Updated `cargo contract new` template dependencies to ink! `3` - [#569](https://github.com/paritytech/cargo-contract/pull/569)
+- Improved documentation on how to invoke `cargo contract decode` - [#572](https://github.com/paritytech/cargo-contract/pull/572)
 
 ## [1.3.0] - 2022-05-09
 
@@ -53,7 +54,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Interact with contracts: upload, instantiate and call commands
 
 We added commands to upload, instantiate and call contracts!
-This allows interacting with contracts on live chains with a compatible 
+This allows interacting with contracts on live chains with a compatible
 [`pallet-contracts`](https://github.com/paritytech/substrate/tree/master/frame/contracts).
 
 For command-line examples on how to use these commands see [#79](https://github.com/paritytech/cargo-contract/pull/79).

README.md

@@ -3,12 +3,14 @@
 
 [![CI Status][a1]][a2]
 [![Latest Release][d1]][d2]
+[![stack-exchange][s1]][s2]
 
 [a1]: https://gitlab.parity.io/parity/mirrors/cargo-contract/badges/master/pipeline.svg
 [a2]: https://gitlab.parity.io/parity/mirrors/cargo-contract/pipelines
-[b2]: https://substrate.stackexchange.com/questions/tagged/ink?tab=Votes
 [d1]: https://img.shields.io/crates/v/cargo-contract.svg
 [d2]: https://crates.io/crates/cargo-contract
+[s1]: https://img.shields.io/badge/click-white.svg?logo=StackExchange&label=ink!%20Support%20on%20StackExchange&labelColor=white&color=blue
+[s2]: https://substrate.stackexchange.com/questions/tagged/ink?tab=Votes
 
 <p align="center">
 
@@ -17,15 +19,15 @@
 
 <br/>
 
-[Guided Tutorial for Beginners](https://docs.substrate.io/tutorials/v3/ink-workshop/pt1/)&nbsp;&nbsp;•&nbsp;&nbsp; 
-[ink! Documentation Portal](https://paritytech.github.io/ink-docs)
+[Guided Tutorial for Beginners](https://docs.substrate.io/tutorials/v3/ink-workshop/pt1/)&nbsp;&nbsp;•&nbsp;&nbsp;
+[ink! Documentation Portal](https://ink.substrate.io)
 
 <br/>
 </div>
 
 More relevant links:
-* Find answers to your questions by joining our [Stack Exchange][b2] community
-* [`ink!`](https://github.com/paritytech/ink) ‒ The main ink! repository with smart contract examples
+* Find answers to your questions by joining our [Stack Exchange][s2] community
+* [ink!](https://github.com/paritytech/ink) ‒ The main ink! repository with smart contract examples
 * [Contracts UI](https://paritytech.github.io/contracts-ui/) ‒ Frontend for contract deployment and interaction
 * [Substrate Contracts Node](https://github.com/paritytech/substrate-contracts-node) ‒ Simple Substrate blockchain which includes smart contract functionality
 
@@ -41,7 +43,7 @@ More relevant links:
   * [Arch Linux](https://archlinux.org/packages/community/x86_64/binaryen/): `pacman -S binaryen`
   * Windows: [binary releases are available](https://github.com/WebAssembly/binaryen/releases)
 
-  There's only an old version in your distributions package manager? Just use a 
+  There's only an old version in your distributions package manager? Just use a
   [binary release](https://github.com/WebAssembly/binaryen/releases).
 
 * Step 3: Install `dylint`
@@ -87,7 +89,7 @@ e.g. `cargo contract new --help`.
 Creates an initial smart contract with some scaffolding code into a new
 folder `my_contract` .
 
-The contract contains the source code for the [`Flipper`](https://github.com/paritytech/ink/blob/master/examples/flipper/lib.rs) 
+The contract contains the source code for the [`Flipper`](https://github.com/paritytech/ink/blob/master/examples/flipper/lib.rs)
 contract, which is about the simplest "smart" contract you can build ‒ a `bool` which gets flipped
 from `true` to `false` through the `flip()` function.
 
@@ -125,6 +127,14 @@ Create an instance of a contract on chain. See [extrinsics](docs/extrinsics.md).
 
 Invoke a message on an existing contract on chain. See [extrinsics](docs/extrinsics.md).
 
+##### `cargo contract decode`
+
+Decodes a contracts input or output data.
+
+This can be either an event, an invocation of a contract message, or an invocation of a contract constructor.
+
+The argument has to be given as hex-encoding, starting with `0x`.
+
 ## License
 
 The entire code within this repository is licensed under the [GPLv3](LICENSE).

src/cmd/decode.rs

@@ -29,12 +29,15 @@ use anyhow::{
 use colored::Colorize as _;
 
 #[derive(Debug, Clone, clap::Args)]
-#[clap(name = "decode", about = "Decode input_data for a contract")]
+#[clap(
+    name = "decode",
+    about = "Decodes the input or output data of a contract"
+)]
 pub struct DecodeCommand {
-    /// Type of data
+    /// The type of data to encode.
     #[clap(arg_enum, short, long)]
     r#type: DataType,
-    /// The data to decode
+    /// The data to decode; this has to be a hex value starting with `0x`.
     #[clap(short, long)]
     data: String,
 }

src/cmd/extrinsics/call.rs

@@ -84,7 +84,7 @@ impl CallCommand {
             load_metadata(self.extrinsic_opts.manifest_path.as_ref())?;
         let transcoder = ContractMessageTranscoder::new(&contract_metadata);
         let call_data = transcoder.encode(&self.message, &self.args)?;
-        log::debug!("message data: {:?}", hex::encode(&call_data));
+        log::debug!("Message data: {:?}", hex::encode(&call_data));
 
         let signer = super::pair_signer(self.extrinsic_opts.signer()?);
 

src/cmd/extrinsics/transcode/mod.rs

@@ -207,7 +207,7 @@ impl<'a> ContractMessageTranscoder<'a> {
                     variant_index
                 )
             })?;
-        log::debug!("decoding contract event '{}'", event_spec.label());
+        log::debug!("Decoding contract event '{}'", event_spec.label());
 
         let mut args = Vec::new();
         for arg in event_spec.args() {
@@ -234,7 +234,7 @@ impl<'a> ContractMessageTranscoder<'a> {
                     hex::encode(&msg_selector)
                 )
             })?;
-        log::debug!("decoding contract message '{}'", msg_spec.label());
+        log::debug!("Decoding contract message '{}'", msg_spec.label());
 
         let mut args = Vec::new();
         for arg in msg_spec.args() {
@@ -261,7 +261,7 @@ impl<'a> ContractMessageTranscoder<'a> {
                     hex::encode(&msg_selector)
                 )
             })?;
-        log::debug!("decoding contract constructor '{}'", msg_spec.label());
+        log::debug!("Decoding contract constructor '{}'", msg_spec.label());
 
         let mut args = Vec::new();
         for arg in msg_spec.args() {

src/main.rs

@@ -465,7 +465,7 @@ enum Command {
     /// Call a contract
     #[clap(name = "call")]
     Call(CallCommand),
-    /// Decode a contract input data
+    /// Decodes a contracts input or output data (supplied in hex-encoding)
     #[clap(name = "decode")]
     Decode(DecodeCommand),
 }