Minor tweaks to the README

Cargo.toml

@@ -4,6 +4,7 @@ version = "0.1.0"
 authors = ["Parity Technologies <admin@parity.io>"]
 edition = "2018"
 license = "GPLv3+"
+default-run = "ledgeracio"
 
 [dependencies]
 substrate-subxt = { git = "https://github.com/paritytech/substrate-subxt.git", branch = "no-sync-required" }

README.md

@@ -295,8 +295,8 @@ given index.
 #### Announcing an intention to validate: `ledgeracio validator announce <index> [commission]`
 
 This command announces that the controller account at `<index>` intends to
-validate.  An optional commission (in parts per billion) may also be provided.  If none is supplied, it
-defaults to 10⁹ parts per billion, or 100%.
+validate.  An optional commission (as a decimal between 0 and 1 inclusive) may also be provided.  If none is supplied, it
+defaults to 1, or 100%.
 
 #### Cease validation: `ledgeracio validator chill`
 

src/bin/ledgeracio/common.rs

@@ -143,9 +143,36 @@ pub fn pad(mut zeros: u8, value: u128) -> String {
     value
 }
 
+pub fn parse_ppb(data: &str) -> Result<u32, Error> {
+    if data == "1" {
+        Ok(1_000_000_000)
+    } else if data == "0" {
+        Ok(0)
+    } else if !data.starts_with("0.") {
+        Err(
+            "Commission must start with 0. or be equal to 1 (the default) or 0"
+                .to_owned()
+                .into(),
+        )
+    } else if data.len() > 11 {
+        Err("Commission too long.  Check for excess trailing zeroes."
+            .to_owned()
+            .into())
+    } else {
+        let mut len = data.len() - 2;
+        let mut res: u32 = str::parse(&data[2..])?;
+        while len < 9 {
+            res *= 10;
+            len += 1;
+        }
+        Ok(res)
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
+
     #[test]
     fn padding_works() {
         assert_eq!(pad(0, 100), "100".to_owned());
@@ -154,4 +181,16 @@ mod tests {
         assert_eq!(pad(3, 10001), "10.001".to_owned());
         assert_eq!(pad(3, 10010), "10.01".to_owned());
     }
+
+    #[test]
+    fn parse_ppb_works() {
+        assert_eq!(parse_ppb("1").unwrap(), 1_000_000_000);
+        assert_eq!(parse_ppb("0").unwrap(), 0);
+        assert!(parse_ppb("0.").is_err());
+        assert_eq!(parse_ppb("0.01").unwrap(), 10_000_000);
+        assert!(parse_ppb("0.0100000000").is_err());
+        assert_eq!(parse_ppb("0.010000000").unwrap(), 10_000_000);
+        assert_eq!(parse_ppb("0.000000000").unwrap(), 0);
+        assert_eq!(parse_ppb("0.999999999").unwrap(), 999_999_999);
+    }
 }

src/bin/ledgeracio/validator.rs

@@ -18,7 +18,8 @@
 //! e.g. rotating session keys, set payment target, announcing
 //! intention to validate etc. Requires a network connection.
 
-use super::{parse_reward_destination, AccountType, AddressSource, Error, LedgeracioPath, StructOpt};
+use super::{common::parse_ppb, parse_reward_destination, AccountType, AddressSource, Error,
+            LedgeracioPath, StructOpt};
 use codec::Decode;
 use core::{future::Future, pin::Pin};
 use ledgeracio::parse_address;
@@ -42,7 +43,11 @@ pub(crate) enum Validator {
     /// specified.
     Show { index: Option<u32> },
     /// Announce intention to validate
-    Announce { index: u32, commission: Option<u32> },
+    Announce {
+        index: u32,
+        #[structopt(parse(try_from_str = parse_ppb))]
+        commission: Option<u32>,
+    },
     /// Chill (announce intention to cease validation)
     Chill { index: u32 },
     /// Replace a session key