Implement Display trait for ChainId and DidPkh

src/identity/did_pkh.rs

@@ -1,5 +1,6 @@
 /// https://github.com/w3c-ccg/did-pkh/blob/main/did-pkh-method-draft.md
 use std::convert::TryInto;
+use std::fmt;
 use std::str::FromStr;
 
 use regex::Regex;
@@ -8,6 +9,9 @@ use crate::utils::caip2::ChainId;
 use crate::utils::currencies::Currency;
 use super::did::DidParseError;
 
+// https://github.com/ChainAgnostic/CAIPs/blob/master/CAIPs/caip-10.md#syntax
+const DID_PKH_RE: &str = r"did:pkh:(?P<network>[-a-z0-9]{3,8}):(?P<chain>[-a-zA-Z0-9]{1,32}):(?P<address>[a-zA-Z0-9]{1,64})";
+
 #[derive(Clone, Debug, PartialEq)]
 pub struct DidPkh {
     pub chain_id: ChainId,
@@ -29,20 +33,18 @@ impl DidPkh {
     }
 }
 
-impl ToString for DidPkh {
-    fn to_string(&self) -> String {
-        format!(
+impl fmt::Display for DidPkh {
+    fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
+        let did_str = format!(
             "did:pkh:{}:{}:{}",
             self.chain_id.namespace,
             self.chain_id.reference,
             self.address,
-        )
+        );
+        write!(formatter, "{}", did_str)
     }
 }
 
-// https://github.com/ChainAgnostic/CAIPs/blob/master/CAIPs/caip-10.md#syntax
-const DID_PKH_RE: &str = r"did:pkh:(?P<network>[-a-z0-9]{3,8}):(?P<chain>[-a-zA-Z0-9]{1,32}):(?P<address>[a-zA-Z0-9]{1,64})";
-
 impl FromStr for DidPkh {
     type Err = DidParseError;
 

src/utils/caip2.rs

@@ -1,4 +1,5 @@
 /// https://github.com/ChainAgnostic/CAIPs/blob/master/CAIPs/caip-2.md
+use std::fmt;
 use std::str::FromStr;
 
 use regex::Regex;
@@ -59,9 +60,9 @@ impl FromStr for ChainId {
     }
 }
 
-impl ToString for ChainId {
-    fn to_string(&self) -> String {
-        format!("{}:{}", self.namespace, self.reference)
+impl fmt::Display for ChainId {
+    fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(formatter, "{}:{}", self.namespace, self.reference)
     }
 }