From: Ian Jackson <ijackson@chiark.greenend.org.uk>
Date: Tue, 10 Jan 2023 00:01:00 +0000 (+0000)
Subject: Config inspection: make InspectableConfig impl dyn despatch
X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~ian/git?a=commitdiff_plain;h=0fc6d1b17b750c4e29e5901ec8ce768dd9c33e6b;p=hippotat.git

Config inspection: make InspectableConfig impl dyn despatch

Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>
---

diff --git a/src/config.rs b/src/config.rs
index 13605d5..1ecc479 100644
--- a/src/config.rs
+++ b/src/config.rs
@@ -95,12 +95,16 @@ pub trait InspectableConfig {
                  -> Option<&dyn InspectableConfigValue>;
 
   #[throws(AE)]
-  fn implement_print_config(&self, key: &str) {
-    if let Some(inspectable) = self.inspect_key(key) {
-      println!("{}", DisplayInspectable(inspectable));
-    } else {
-      throw!(anyhow!("unknown config key {:?}", key));
+  fn implement_print_config(&self, key: &str) where Self: Sized {
+    #[throws(AE)]
+    fn inner(self_: &dyn InspectableConfig, key: &str) {
+      if let Some(inspectable) = self_.inspect_key(key) {
+        println!("{}", DisplayInspectable(inspectable));
+      } else {
+        throw!(anyhow!("unknown config key {:?}", key));
+      }
     }
+    inner(self, key)?;
   }
 }