From eb0473df93b49d6a2ff50f82e435dbd2e19467c7 Mon Sep 17 00:00:00 2001
From: Steven Fackler <sfackler@gmail.com>
Date: Fri, 11 Apr 2014 20:59:18 -0700
Subject: Make Result::{unwrap, unwrap_err} require Show

`foo.ok().unwrap()` and `foo.err().unwrap()` are the fallbacks for types
that aren't `Show`.

Closes #13379
---
 src/libstd/result.rs | 33 +++++++++++++++++++--------------
 1 file changed, 19 insertions(+), 14 deletions(-)

(limited to 'src/libstd/result.rs')

diff --git a/src/libstd/result.rs b/src/libstd/result.rs
index 8bd36127db2..9ca1443ea50 100644
--- a/src/libstd/result.rs
+++ b/src/libstd/result.rs
@@ -12,6 +12,7 @@
 
 use clone::Clone;
 use cmp::Eq;
+use std::fmt::Show;
 use iter::{Iterator, FromIterator};
 use option::{None, Option, Some};
 
@@ -174,46 +175,50 @@ impl<T, E> Result<T, E> {
         }
     }
 
-    /////////////////////////////////////////////////////////////////////////
-    // Common special cases
-    /////////////////////////////////////////////////////////////////////////
-
     /// Unwraps a result, yielding the content of an `Ok`.
-    /// Fails if the value is an `Err`.
+    /// Else it returns `optb`.
     #[inline]
-    pub fn unwrap(self) -> T {
+    pub fn unwrap_or(self, optb: T) -> T {
         match self {
             Ok(t) => t,
-            Err(_) => fail!("called `Result::unwrap()` on an `Err` value")
+            Err(_) => optb
         }
     }
 
     /// Unwraps a result, yielding the content of an `Ok`.
-    /// Else it returns `optb`.
+    /// If the value is an `Err` then it calls `op` with its value.
     #[inline]
-    pub fn unwrap_or(self, optb: T) -> T {
+    pub fn unwrap_or_handle(self, op: |E| -> T) -> T {
         match self {
             Ok(t) => t,
-            Err(_) => optb
+            Err(e) => op(e)
         }
     }
+}
 
+impl<T, E: Show> Result<T, E> {
     /// Unwraps a result, yielding the content of an `Ok`.
-    /// If the value is an `Err` then it calls `op` with its value.
+    ///
+    /// Fails if the value is an `Err`.
     #[inline]
-    pub fn unwrap_or_handle(self, op: |E| -> T) -> T {
+    pub fn unwrap(self) -> T {
         match self {
             Ok(t) => t,
-            Err(e) => op(e)
+            Err(e) =>
+                fail!("called `Result::unwrap()` on an `Err` value: {}", e)
         }
     }
+}
 
+impl<T: Show, E> Result<T, E> {
     /// Unwraps a result, yielding the content of an `Err`.
+    ///
     /// Fails if the value is an `Ok`.
     #[inline]
     pub fn unwrap_err(self) -> E {
         match self {
-            Ok(_) => fail!("called `Result::unwrap_err()` on an `Ok` value"),
+            Ok(t) =>
+                fail!("called `Result::unwrap_err()` on an `Ok` value: {}", t),
             Err(e) => e
         }
     }
-- 
cgit 1.4.1-3-g733a5