Github user anatol commented on a diff in the pull request:
https://github.com/apache/thrift/pull/1147#discussion_r97210872
--- Diff: lib/rs/src/errors.rs ---
@@ -0,0 +1,678 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements. See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership. The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License. You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied. See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+use std::convert::{From, Into};
+use std::error::Error as StdError;
+use std::fmt::{Debug, Display, Formatter};
+use std::{error, fmt, io, string};
+use try_from::TryFrom;
+
+use ::protocol::{TFieldIdentifier, TInputProtocol, TOutputProtocol,
TStructIdentifier, TType};
+
+// FIXME: should all my error structs impl error::Error as well?
+// FIXME: should all fields in TransportError, ProtocolError and
ApplicationError be optional?
+
+/// Thrift error type.
+///
+/// The error type defined here is used throughout this crate as well as in
+/// all Thrift-compiler-generated Rust code. It falls into one of four
+/// standard (i.e. defined by convention in Thrift implementations)
categories.
+/// These are:
+///
+/// 1. **Transport errors**: errors encountered while writing byes to the
I/O
+/// channel. These include "connection closed", "bind errors", etc.
+/// 2. **Protocol errors**: errors encountered when processing a Thrift
message
+/// within the thrift library. These include "exceeding size limits",
+/// "unsupported protocol versions", etc.
+/// 3. **Application errors**: errors encountered when
Thrift-compiler-generated
+/// 'application' code encounters conditions that violate the spec.
These
+/// include "out-of-order messages", "missing required-field values",
etc.
+/// This category also functions as a catch-all: any error returned by
+/// handler functions is automatically encoded as an `ApplicationError`
and
+/// returned to the caller.
+/// 4. **User errors**: exception structs defined within the Thrift IDL.
+///
+/// With the exception of `Error::User`, each error variant encapsulates a
+/// corresponding struct which encodes two required fields:
+///
+/// 1. kind: an enum indicating what kind of error was encountered
+/// 2. message: string with human-readable error information
+///
+/// These two fields are encoded and sent over the wire to the remote.
`kind`
+/// is defined by convention while `message` is freeform. If none of the
+/// enumerated error kinds seem suitable use the catch-all `Unknown`.
+///
+/// # Examples
+///
+/// Creating a `TransportError` explicitly.
+///
+/// Conversions are defined from `thrift::TransportError`,
`thrift::ProtocolError`
+/// and `thrift::ApplicationError` to the corresponding `thrift::Error`
variant
+/// (see `err2` below).
+///
+/// ```
+/// use thrift;
+/// use thrift::{TransportError, TransportErrorKind};
+///
+/// let err0: thrift::Result<()> = Err(
+/// thrift::Error::Transport(
+/// TransportError {
+/// kind: TransportErrorKind::TimedOut,
+/// message: format!("connection to server timed out")
+/// }
+/// )
+/// );
+///
+/// let err1: thrift::Result<()> = Err(
+/// thrift::Error::Transport(
+/// TransportError::new(
+/// TransportErrorKind::TimedOut,
+/// format!("connection to server timed out")
+/// )
+/// )
+/// );
+///
+/// let err2: thrift::Result<()> = Err(
+/// thrift::Error::from(
+/// TransportError::new(
+/// TransportErrorKind::TimedOut,
+/// format!("connection to server timed out")
+/// )
+/// )
+/// );
+///
+/// ```
+///
+/// Creating an arbitrary error from a string
+///
+/// ```
+/// use thrift;
+/// use thrift::{ApplicationError, ApplicationErrorKind};
+///
+/// let err0: thrift::Result<()> = Err(
+/// thrift::Error::from("This is an error")
+/// );
+///
+/// // err0 is equivalent to...
+///
+/// let err1: thrift::Result<()> = Err(
+/// thrift::Error::Application(
+/// ApplicationError::new(
+/// ApplicationErrorKind::Unknown,
+/// format!("This is an error")
+/// )
+/// )
+/// );
+/// ```
+///
+/// Returning a user-defined (using the Thrift IDL) exception struct.
+///
+/// ```text
+/// // Thrift IDL exception definition.
+/// exception Xception {
+/// 1: i32 errorCode,
+/// 2: string message
+/// }
+/// ```
+///
+/// ```
+/// use std::convert::From;
+/// use std::error::Error;
+/// use std::fmt;
+/// use std::fmt::{Display, Formatter};
+///
+/// // auto-generated by the Thrift compiler
+/// #[derive(Clone, Debug, Eq, Ord, PartialEq, PartialOrd)]
+/// pub struct Xception {
+/// pub error_code: Option<i32>,
+/// pub message: Option<String>,
+/// }
+///
+/// // auto-generated by the Thrift compiler
+/// impl Error for Xception {
+/// fn description(&self) -> &str {
+/// "remote service threw Xception"
+/// }
+/// }
+///
+/// // auto-generated by the Thrift compiler
+/// impl From<Xception> for thrift::Error {
+/// fn from(e: Xception) -> Self {
+/// thrift::Error::User(Box::new(e))
+/// }
+/// }
+///
+/// // auto-generated by the Thrift compiler
+/// impl Display for Xception {
+/// fn fmt(&self, f: &mut Formatter) -> fmt::Result {
+/// self.description().fmt(f)
+/// }
+/// }
+///
+/// // in user code...
+/// let err: thrift::Result<()> = Err(
+/// thrift::Error::from(Xception { error_code: Some(1), message: None })
+/// );
+/// ```
+pub enum Error {
+ /// Errors encountered while writing byes to the I/O channel.
+ ///
+ /// These include "connection closed", "bind errors", etc.
+ Transport(TransportError),
+ /// Errors encountered when processing a Thrift message within the rift
+ /// library.
+ ///
+ /// These include "exceeding size limits", "unsupported protocol
versions",
+ /// etc.
+ Protocol(ProtocolError),
+ /// Errors encountered when Thrift-compiler-generated 'application'
code
+ /// encounters conditions that violate the spec.
+ ///
+ /// These include "out-of-order messages", "missing required-field
values",
+ /// etc. This variant also functions as a catch-all: any error
returned by
+ /// handler functions is automatically encoded as an
`ApplicationError` and
+ /// returned to the caller.
+ Application(ApplicationError),
+ /// Carries exception structs defined within the Thrift IDL.
+ User(Box<error::Error + Sync + Send>),
+}
+
+impl Error {
+ /// Read the wire representation of an application exception thrown by
the
+ /// remote Thrift endpoint into its corresponding rift
`ApplicationError`
+ /// representation.
+ ///
+ /// Application code should never call this method directly.
+ pub fn read_application_error_from_in_protocol(i: &mut TInputProtocol)
+ ->
::Result<ApplicationError> {
+ let mut message = "general remote error".to_owned();
+ let mut kind = ApplicationErrorKind::Unknown;
+
+ try!(i.read_struct_begin());
--- End diff --
It should probably use shorter and nicer `?` operator instead of `try!`
macro. Here and everywhere else. I counted ~50 usages of `try!` macro.
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