feat: add cast sig (#645)

* feat: cast sig

* docs: update cast feature list

cast/README.md

@@ -39,6 +39,7 @@
 - [x] `calldata`
 - [x] `chain`
 - [x] `chain-id`
+- [x] `client` 
 - [x] `code`
 - [ ] `debug`
 - [x] `estimate`
@@ -58,6 +59,7 @@
 - [x] `resolve-name`
 - [ ] `run-tx`
 - [x] `send` (partial)
+- [x] `sig`
 - [ ] `sign`
 - [x] `storage`
 - [x] `tx`

cli/src/cast.rs

@@ -7,7 +7,9 @@ use cast::{Cast, SimpleCast};
 mod opts;
 use cast::InterfacePath;
 use ethers::{
+    contract::BaseContract,
     core::{
+        abi::parse_abi,
         rand::thread_rng,
         types::{BlockId, BlockNumber::Latest},
     },
@@ -446,6 +448,11 @@ async fn main() -> eyre::Result<()> {
                 SimpleCast::etherscan_source(chain.inner, address, etherscan_api_key).await?
             );
         }
+        Subcommands::Sig { sig } => {
+            let contract = BaseContract::from(parse_abi(&[&sig]).unwrap());
+            let selector = contract.abi().functions().last().unwrap().short_signature();
+            println!("0x{}", hex::encode(selector));
+        }
         Subcommands::Wallet { command } => match command {
             WalletSubcommands::New { path, password, unsafe_password } => {
                 let mut rng = thread_rng();

cli/src/opts/cast.rs

@@ -402,6 +402,11 @@ pub enum Subcommands {
         #[clap(flatten)]
         chain: ClapChain,
     },
+    #[clap(name = "sig", about = "Print a function's 4-byte selector")]
+    Sig {
+        #[clap(help = "The human-readable function signature, e.g. 'transfer(address,uint256)'")]
+        sig: String,
+    },
     #[clap(about = "generate shell completions script")]
     Completions {
         #[clap(arg_enum)]