log feature - support use of the log crate

.gitignore

@@ -1,3 +1,4 @@
 *~
 target/
-Cargo.lock
+Cargo.lock
+rusty-tags.vi

.travis.yml

@@ -38,9 +38,12 @@ env:
   - RUSTFLAGS="-D warnings"
   matrix:
   - FEATURES=--features=backtrace
+  - FEATURES=--features=log
   - FEATURES=--no-default-features
 
 matrix:
   exclude:
   - env: FEATURES=--features=backtrace
     rust: 1.10.0
+  - env: FEATURES=--features=log
+    rust: 1.10.0

Cargo.toml

@@ -24,3 +24,4 @@ example_generated = []
 
 [dependencies]
 backtrace = { version = "0.3.3", optional = true }
+log = { version = "0.3", optional = true }

examples/all.rs

@@ -1,3 +1,6 @@
+#[cfg(feature = "log")]
+#[macro_use]
+extern crate log;
 #[macro_use]
 extern crate error_chain;
 

examples/chain_err.rs

@@ -1,6 +1,9 @@
 //! Demonstrates usage of `Error::caused` method. This method enables chaining errors
 //! like `ResultExt::chain_err` but doesn't require the presence of a `Result` wrapper.
 
+#[cfg(feature = "log")]
+#[macro_use]
+extern crate log;
 #[macro_use]
 extern crate error_chain;
 

examples/doc.rs

@@ -2,6 +2,9 @@
 
 //! This module is used to check that all generated items are documented.
 
+#[cfg(feature = "log")]
+#[macro_use]
+extern crate log;
 #[macro_use]
 extern crate error_chain;
 

examples/quickstart.rs

@@ -6,6 +6,9 @@
 
 // Import the macro. Don't forget to add `error-chain` in your
 // `Cargo.toml`!
+#[cfg(feature = "log")]
+#[macro_use]
+extern crate log;
 #[macro_use]
 extern crate error_chain;
 

examples/size.rs

@@ -1,3 +1,6 @@
+#[cfg(feature = "log")]
+#[macro_use]
+extern crate log;
 #[macro_use]
 extern crate error_chain;
 

src/bin/has_backtrace.rs

@@ -2,9 +2,14 @@
 //! Used by tests to make sure backtraces are available when they should be. Should not be used
 //! outside of the tests.
 
+#[cfg(feature = "log")]
+#[macro_use]
+extern crate log;
 #[macro_use]
 extern crate error_chain;
 
+
+
 error_chain! {
     errors {
         MyError

src/error_chain.rs

@@ -10,22 +10,62 @@ macro_rules! impl_error_chain_processed {
         impl_error_chain_processed! {
             types {
                 Error, ErrorKind, ResultExt, Result;
+                result_log_ext = ResultLogExt;
             }
             $( $rest )*
         }
     };
-    // With `Result` wrapper.
+    // with result wrapper and logext
     (
         types {
             $error_name:ident, $error_kind_name:ident,
             $result_ext_name:ident, $result_name:ident;
+            result_log_ext = $result_log_ext_name:ident;
         }
         $( $rest: tt )*
     ) => {
         impl_error_chain_processed! {
             types {
                 $error_name, $error_kind_name,
                 $result_ext_name;
+                result_log_ext = $result_log_ext_name;
+            }
+            $( $rest )*
+        }
+        /// Convenient wrapper around `std::Result`.
+        #[allow(unused)]
+        pub type $result_name<T> = ::std::result::Result<T, $error_name>;
+    };
+    // without result wrapper and no logext
+    (
+        types {
+            $error_name:ident, $error_kind_name:ident,
+            $result_ext_name:ident;
+        }
+        $( $rest: tt )*
+    ) => {
+        impl_error_chain_processed! {
+            types {
+                $error_name, $error_kind_name,
+                $result_ext_name;
+                result_log_ext = ResultLogExt3;
+            }
+            $( $rest )*
+        }
+    };
+    // With `Result` wrapper no log ext
+    (
+        types {
+            $error_name:ident, $error_kind_name:ident,
+            $result_ext_name:ident, $result_name:ident;
+        }
+        $( $rest: tt )*
+    ) => {
+        impl_error_chain_processed! {
+            types {
+                $error_name, $error_kind_name,
+                $result_ext_name;
+                result_log_ext = ResultLogExti2;
             }
             $( $rest )*
         }
@@ -38,6 +78,7 @@ macro_rules! impl_error_chain_processed {
         types {
             $error_name:ident, $error_kind_name:ident,
             $result_ext_name:ident;
+            result_log_ext = $result_log_ext_name:ident;
         }
 
         links {
@@ -342,6 +383,9 @@ macro_rules! impl_error_chain_processed {
         }
 
 
+        #[cfg(feature = "log")]
+        impl_result_log_ext!{ $result_log_ext_name , $error_name }
+
     };
 }
 

src/lib.rs

@@ -101,6 +101,8 @@
 //! define an `errors` module and inside it call [`error_chain!`]:
 //!
 //! ```
+//! # #[cfg(feature = "log")]
+//! # #[macro_use] extern crate log;
 //! # #[macro_use] extern crate error_chain;
 //! mod other_error {
 //!     error_chain! {}
@@ -182,6 +184,8 @@
 //! Introducing new error chains, with a string message:
 //!
 //! ```
+//! # #[cfg(feature = "log")]
+//! # #[macro_use] extern crate log;
 //! # #[macro_use] extern crate error_chain;
 //! # fn main() {}
 //! # error_chain! {}
@@ -193,6 +197,8 @@
 //! Introducing new error chains, with an [`ErrorKind`]:
 //!
 //! ```
+//! # #[cfg(feature = "log")]
+//! # #[macro_use] extern crate log;
 //! # #[macro_use] extern crate error_chain;
 //! # fn main() {}
 //! error_chain! {
@@ -216,6 +222,8 @@
 //! So the below is equivalent to the previous:
 //!
 //! ```
+//! # #[cfg(feature = "log")]
+//! # #[macro_use] extern crate log;
 //! # #[macro_use] extern crate error_chain;
 //! # fn main() {}
 //! # error_chain! { errors { FooError } }
@@ -237,6 +245,8 @@
 //! With [`bail!`] the previous examples look like:
 //!
 //! ```
+//! # #[cfg(feature = "log")]
+//! # #[macro_use] extern crate log;
 //! # #[macro_use] extern crate error_chain;
 //! # fn main() {}
 //! # error_chain! { errors { FooError } }
@@ -264,6 +274,8 @@
 //! To extend the error chain:
 //!
 //! ```
+//! # #[cfg(feature = "log")]
+//! # #[macro_use] extern crate log;
 //! # #[macro_use] extern crate error_chain;
 //! # fn main() {}
 //! # error_chain! {}
@@ -290,6 +302,8 @@
 //! To chain an error directly, use [`with_chain`]:
 //!
 //! ```
+//! # #[cfg(feature = "log")]
+//! # #[macro_use] extern crate log;
 //! # #[macro_use] extern crate error_chain;
 //! # fn main() {}
 //! # error_chain! {}
@@ -306,6 +320,8 @@
 //! To convert an error from another error chain to this error chain:
 //!
 //! ```
+//! # #[cfg(feature = "log")]
+//! # #[macro_use] extern crate log;
 //! # #[macro_use] extern crate error_chain;
 //! # fn main() {}
 //! # mod other { error_chain! {} }
@@ -334,6 +350,8 @@
 //! making dispatching on error kinds relatively compact:
 //!
 //! ```
+//! # #[cfg(feature = "log")]
+//! # #[macro_use] extern crate log;
 //! # #[macro_use] extern crate error_chain;
 //! # fn main() {
 //! error_chain! {
@@ -356,6 +374,8 @@
 //! Chained errors are also matched with (relatively) compact syntax
 //!
 //! ```
+//! # #[cfg(feature = "log")]
+//! # #[macro_use] extern crate log;
 //! # #[macro_use] extern crate error_chain;
 //! mod utils {
 //!     error_chain! {
@@ -390,6 +410,8 @@
 //! of causing errors. For reporting purposes, this information can be accessed as follows.
 //!
 //! ```
+//! # #[cfg(feature = "log")]
+//! # #[macro_use] extern crate log;
 //! # #[macro_use] extern crate error_chain;
 //! use error_chain::ChainedError;  // for e.display_chain()
 //!
@@ -466,6 +488,8 @@
 //! within your own project.
 //!
 //! ```
+//! # #[cfg(feature = "log")]
+//! # #[macro_use] extern crate log;
 //! # #[macro_use]
 //! # extern crate error_chain;
 //! # mod errors {
@@ -540,6 +564,13 @@ use std::error;
 use std::iter::Iterator;
 use std::fmt;
 
+#[cfg(feature = "log")]
+#[macro_use]
+extern crate log;
+
+#[macro_use]
+mod log_ext;
+
 #[macro_use]
 mod impl_error_chain_kind;
 #[macro_use]
@@ -692,6 +723,8 @@ impl State {
 /// `bail!(expr)` is equivalent to writing.
 ///
 /// ```
+/// # #[cfg(feature = "log")]
+/// # #[macro_use] extern crate log;
 /// # #[macro_use] extern crate error_chain;
 /// # error_chain! { }
 /// # fn main() { }
@@ -704,6 +737,8 @@ impl State {
 /// And as shorthand it takes a formatting string a la `println!`:
 ///
 /// ```
+/// # #[cfg(feature = "log")]
+/// # #[macro_use] extern crate log;
 /// # #[macro_use] extern crate error_chain;
 /// # error_chain! { }
 /// # fn main() { }
@@ -718,6 +753,8 @@ impl State {
 /// Bailing on a custom error:
 ///
 /// ```
+/// # #[cfg(feature = "log")]
+/// # #[macro_use] extern crate log;
 /// # #[macro_use] extern crate error_chain;
 /// # fn main() {}
 /// error_chain! {
@@ -738,6 +775,8 @@ impl State {
 /// Bailing on a formatted string:
 ///
 /// ```
+/// # #[cfg(feature = "log")]
+/// # #[macro_use] extern crate log;
 /// # #[macro_use] extern crate error_chain;
 /// # fn main() {}
 /// error_chain! { }
@@ -770,6 +809,8 @@ macro_rules! bail {
 /// As an example, `ensure!(condition, "error code: {}", errcode)` is equivalent to
 ///
 /// ```
+/// # #[cfg(feature = "log")]
+/// # #[macro_use] extern crate log;
 /// # #[macro_use] extern crate error_chain;
 /// # error_chain! { }
 /// # fn main() { }