feat: impl FromEnv for SignetConstants types

Author: anna-carroll

src/utils/from_env.rs

@@ -613,7 +613,41 @@ impl_for_parseable!(
     i128,
     isize,
     url::Url,
-    tracing::Level,
+    tracing::Level
+);
+
+/// EnvItemInfo for .env variable holding chain name
+/// Used to implement FromEnv for SignetConstants type structs
+/// that can be instantiated from a single chain name
+static CHAIN_NAME: EnvItemInfo = EnvItemInfo {
+    var: "CHAIN_NAME",
+    description: "The name of the chain, e.g. `pecorino`",
+    optional: false,
+};
+
+macro_rules! impl_from_chain {
+    ($($t:ty),*) => {
+        $(
+            // first, impl FromEnvVar for the type
+            impl_for_parseable!($t);
+
+            // next, impl FromEnv using FromEnvVar using the CHAIN_NAME env var
+            impl FromEnv for $t {
+                type Error = <$t as FromStr>::Err;
+
+                fn inventory() -> Vec<&'static EnvItemInfo> {
+                    vec![&CHAIN_NAME]
+                }
+
+                fn from_env() -> Result<Self, FromEnvErr<Self::Error>> {
+                    Self::from_env_var(CHAIN_NAME.var)
+                }
+            }
+        )*
+    }
+}
+
+impl_from_chain!(
     SignetConstants,
     SignetEnvironmentConstants,
     SignetSystemConstants,