Add context method to Error

src/context.rs

@@ -29,7 +29,7 @@ where
         self.map_err(|error| Error::from(ContextError { error, context }))
     }
 
-    fn with_context<C, F>(self, f: F) -> Result<T, Error>
+    fn with_context<C, F>(self, context: F) -> Result<T, Error>
     where
         C: Display + Send + Sync + 'static,
         F: FnOnce() -> C,
@@ -37,7 +37,7 @@ where
         self.map_err(|error| {
             Error::from(ContextError {
                 error,
-                context: f(),
+                context: context(),
             })
         })
     }
@@ -48,26 +48,21 @@ impl<T> Context<T, Error> for Result<T, Error> {
     where
         C: Display + Send + Sync + 'static,
     {
-        self.map_err(|error| Error::from(ContextError { error, context }))
+        self.map_err(|error| error.context(context))
     }
 
-    fn with_context<C, F>(self, f: F) -> Result<T, Error>
+    fn with_context<C, F>(self, context: F) -> Result<T, Error>
     where
         C: Display + Send + Sync + 'static,
         F: FnOnce() -> C,
     {
-        self.map_err(|error| {
-            Error::from(ContextError {
-                error,
-                context: f(),
-            })
-        })
+        self.map_err(|error| error.context(context()))
     }
 }
 
-struct ContextError<E, C> {
-    error: E,
-    context: C,
+pub(crate) struct ContextError<E, C> {
+    pub error: E,
+    pub context: C,
 }
 
 impl<E, C> Debug for ContextError<E, C>

src/error.rs

@@ -1,3 +1,4 @@
+use crate::context::ContextError;
 use std::any::TypeId;
 use std::backtrace::{Backtrace, BacktraceStatus};
 use std::error::Error as StdError;
@@ -66,6 +67,17 @@ impl Error {
         }
     }
 
+    /// Wrap the error value with additional context.
+    pub fn context<C>(self, context: C) -> Self
+    where
+        C: Display + Send + Sync + 'static,
+    {
+        Error::from(ContextError {
+            error: self,
+            context,
+        })
+    }
+
     /// View this error object as the underlying error.
     pub fn as_dyn_error(&self) -> &(dyn StdError + Send + Sync + 'static) {
         &**self