Switch to dtolnay's `thiserror` for handling error boilerplate

Currently CPAL only really uses `failure` for its `derive` capabilities
and the ability to easily generate implementations for `Display`. That
said there are a few issues with using the `failure` crate:

- `failure` does not provie a `std::error::Error` implementation without
  first converting error types into `failure::Error`.
- It leaks significantly into the public API and expects downstream
  users to also depend on `failure` and the non-std `Fail` trait for
  their own error handling.
- Solved problems such as downcasting of causal errors which have since
  been addressed in `std`.
- Provides application-friendly `Fail` trait and `failure::Error` type,
  not particularly useful to libraries like CPAL.

The [`thiserror` crate](https://github.com/dtolnay/thiserror) is better
targeted towards libraries, does not leak into the public API while
providing easy generation of `Display`, `From` and `std::error::Error`
implementations including proper handling of the newish
`std::error::Error::source` method.
This commit is contained in:
mitchmindtree 2019-10-13 12:07:49 +02:00
parent be54ffff09
commit d9d4a906c9
3 changed files with 43 additions and 99 deletions

View File

@ -12,7 +12,7 @@ keywords = ["audio", "sound"]
asio = ["asio-sys"] # Only available on Windows. See README for setup instructions.
[dependencies]
failure = "0.1.5"
thiserror = "1.0.2"
lazy_static = "1.3"
num-traits = "0.2.6"

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@ -1,8 +1,8 @@
use failure::Fail;
use thiserror::Error;
/// The requested host, although supported on this platform, is unavailable.
#[derive(Clone, Debug, Fail)]
#[fail(display = "the requested host is unavailable")]
#[derive(Clone, Debug, Error)]
#[error("the requested host is unavailable")]
pub struct HostUnavailable;
/// Some error has occurred that is specific to the backend from which it was produced.
@ -17,101 +17,95 @@ pub struct HostUnavailable;
/// **Note:** If you notice a `BackendSpecificError` that you believe could be better handled in a
/// cross-platform manner, please create an issue or submit a pull request with a patch that adds
/// the necessary error variant to the appropriate error enum.
#[derive(Clone, Debug, Fail)]
#[fail(display = "A backend-specific error has occurred: {}", description)]
#[derive(Clone, Debug, Error)]
#[error("A backend-specific error has occurred: {description}")]
pub struct BackendSpecificError {
pub description: String,
}
/// An error that might occur while attempting to enumerate the available devices on a system.
#[derive(Debug, Fail)]
#[derive(Debug, Error)]
pub enum DevicesError {
/// See the `BackendSpecificError` docs for more information about this error variant.
#[fail(display = "{}", err)]
#[error("{err}")]
BackendSpecific {
#[fail(cause)]
#[from]
err: BackendSpecificError,
},
}
/// An error that may occur while attempting to retrieve a device name.
#[derive(Debug, Fail)]
#[derive(Debug, Error)]
pub enum DeviceNameError {
/// See the `BackendSpecificError` docs for more information about this error variant.
#[fail(display = "{}", err)]
#[error("{err}")]
BackendSpecific {
#[fail(cause)]
#[from]
err: BackendSpecificError,
},
}
/// Error that can happen when enumerating the list of supported formats.
#[derive(Debug, Fail)]
#[derive(Debug, Error)]
pub enum SupportedFormatsError {
/// The device no longer exists. This can happen if the device is disconnected while the
/// program is running.
#[fail(
display = "The requested device is no longer available. For example, it has been unplugged."
)]
#[error("The requested device is no longer available. For example, it has been unplugged.")]
DeviceNotAvailable,
/// We called something the C-Layer did not understand
#[fail(
display = "Invalid argument passed to the backend. For example, this happens when trying to read capture capabilities when the device does not support it."
#[error(
"Invalid argument passed to the backend. For example, this happens when trying to read capture capabilities when the device does not support it."
)]
InvalidArgument,
/// See the `BackendSpecificError` docs for more information about this error variant.
#[fail(display = "{}", err)]
#[error("{err}")]
BackendSpecific {
#[fail(cause)]
#[from]
err: BackendSpecificError,
},
}
/// May occur when attempting to request the default input or output stream format from a `Device`.
#[derive(Debug, Fail)]
#[derive(Debug, Error)]
pub enum DefaultFormatError {
/// The device no longer exists. This can happen if the device is disconnected while the
/// program is running.
#[fail(
display = "The requested device is no longer available. For example, it has been unplugged."
)]
#[error("The requested device is no longer available. For example, it has been unplugged.")]
DeviceNotAvailable,
/// Returned if e.g. the default input format was requested on an output-only audio device.
#[fail(display = "The requested stream type is not supported by the device.")]
#[error("The requested stream type is not supported by the device.")]
StreamTypeNotSupported,
/// See the `BackendSpecificError` docs for more information about this error variant.
#[fail(display = "{}", err)]
#[error("{err}")]
BackendSpecific {
#[fail(cause)]
#[from]
err: BackendSpecificError,
},
}
/// Error that can happen when creating a `Stream`.
#[derive(Debug, Fail)]
#[derive(Debug, Error)]
pub enum BuildStreamError {
/// The device no longer exists. This can happen if the device is disconnected while the
/// program is running.
#[fail(
display = "The requested device is no longer available. For example, it has been unplugged."
)]
#[error("The requested device is no longer available. For example, it has been unplugged.")]
DeviceNotAvailable,
/// The required format is not supported.
#[fail(display = "The requested stream format is not supported by the device.")]
#[error("The requested stream format is not supported by the device.")]
FormatNotSupported,
/// We called something the C-Layer did not understand
///
/// On ALSA device functions called with a feature they do not support will yield this. E.g.
/// Trying to use capture capabilities on an output only format yields this.
#[fail(display = "The requested device does not support this capability (invalid argument)")]
#[error("The requested device does not support this capability (invalid argument)")]
InvalidArgument,
/// Occurs if adding a new Stream ID would cause an integer overflow.
#[fail(display = "Adding a new stream ID would cause an overflow")]
#[error("Adding a new stream ID would cause an overflow")]
StreamIdOverflow,
/// See the `BackendSpecificError` docs for more information about this error variant.
#[fail(display = "{}", err)]
#[error("{err}")]
BackendSpecific {
#[fail(cause)]
#[from]
err: BackendSpecificError,
},
}
@ -121,15 +115,15 @@ pub enum BuildStreamError {
/// As of writing this, only macOS may immediately return an error while calling this method. This
/// is because both the alsa and wasapi backends only enqueue these commands and do not process
/// them immediately.
#[derive(Debug, Fail)]
#[derive(Debug, Error)]
pub enum PlayStreamError {
/// The device associated with the stream is no longer available.
#[fail(display = "the device associated with the stream is no longer available")]
#[error("the device associated with the stream is no longer available")]
DeviceNotAvailable,
/// See the `BackendSpecificError` docs for more information about this error variant.
#[fail(display = "{}", err)]
#[error("{err}")]
BackendSpecific {
#[fail(cause)]
#[from]
err: BackendSpecificError,
},
}
@ -139,80 +133,30 @@ pub enum PlayStreamError {
/// As of writing this, only macOS may immediately return an error while calling this method. This
/// is because both the alsa and wasapi backends only enqueue these commands and do not process
/// them immediately.
#[derive(Debug, Fail)]
#[derive(Debug, Error)]
pub enum PauseStreamError {
/// The device associated with the stream is no longer available.
#[fail(display = "the device associated with the stream is no longer available")]
#[error("the device associated with the stream is no longer available")]
DeviceNotAvailable,
/// See the `BackendSpecificError` docs for more information about this error variant.
#[fail(display = "{}", err)]
#[error("{err}")]
BackendSpecific {
#[fail(cause)]
#[from]
err: BackendSpecificError,
},
}
/// Errors that might occur while a stream is running.
#[derive(Debug, Fail)]
#[derive(Debug, Error)]
pub enum StreamError {
/// The device no longer exists. This can happen if the device is disconnected while the
/// program is running.
#[fail(
display = "The requested device is no longer available. For example, it has been unplugged."
)]
#[error("The requested device is no longer available. For example, it has been unplugged.")]
DeviceNotAvailable,
/// See the `BackendSpecificError` docs for more information about this error variant.
#[fail(display = "{}", err)]
#[error("{err}")]
BackendSpecific {
#[fail(cause)]
#[from]
err: BackendSpecificError,
},
}
impl From<BackendSpecificError> for DevicesError {
fn from(err: BackendSpecificError) -> Self {
DevicesError::BackendSpecific { err }
}
}
impl From<BackendSpecificError> for DeviceNameError {
fn from(err: BackendSpecificError) -> Self {
DeviceNameError::BackendSpecific { err }
}
}
impl From<BackendSpecificError> for SupportedFormatsError {
fn from(err: BackendSpecificError) -> Self {
SupportedFormatsError::BackendSpecific { err }
}
}
impl From<BackendSpecificError> for DefaultFormatError {
fn from(err: BackendSpecificError) -> Self {
DefaultFormatError::BackendSpecific { err }
}
}
impl From<BackendSpecificError> for BuildStreamError {
fn from(err: BackendSpecificError) -> Self {
BuildStreamError::BackendSpecific { err }
}
}
impl From<BackendSpecificError> for PlayStreamError {
fn from(err: BackendSpecificError) -> Self {
PlayStreamError::BackendSpecific { err }
}
}
impl From<BackendSpecificError> for PauseStreamError {
fn from(err: BackendSpecificError) -> Self {
PauseStreamError::BackendSpecific { err }
}
}
impl From<BackendSpecificError> for StreamError {
fn from(err: BackendSpecificError) -> Self {
StreamError::BackendSpecific { err }
}
}

View File

@ -140,7 +140,6 @@
#![recursion_limit = "512"]
extern crate failure;
#[cfg(target_os = "windows")]
#[macro_use]
extern crate lazy_static;
@ -148,6 +147,7 @@ extern crate lazy_static;
#[cfg(target_os = "emscripten")]
#[macro_use]
extern crate stdweb;
extern crate thiserror;
pub use error::*;
pub use platform::{