unwrap_log/lib.rs
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//! Non-panicking alternatives to `Option` and `Result` unwrapping, which log at warn level.
//!
//! ## Example
//!
//! ```rust
//! use unwrap_log::{OptionExt, ResultExt};
//! use env_logger::Builder;
//! use log::LevelFilter::Warn;
//!
//! Builder::new().filter_level(Warn).init();
//!
//! let x: i32 = None.unwrap_or_default_log();
//! assert_eq!(x, 0);
//!
//! let y: i32 = Err("oops").unwrap_or_default_log();
//! assert_eq!(y, 0);
//! ```
//!
//! Output:
//! ```text
//! [1970-01-01T00:00:00Z WARN my_crate] src\main.rs:8:23 encountered `None`
//! [1970-01-01T00:00:00Z WARN my_crate] src\main.rs:11:30 encountered `Err("oops")`
//! ```
#![no_std]
/// Extension trait providing tracing alternatives to `Option` unwrap methods.
pub trait OptionExt {
/// The type of the "present" output, intended to be `T` for a `Option<T>`.
type Output;
/// Returns the contained `Some` value, or logs at the warn level and returns a default value.
fn unwrap_or_default_log(self) -> Self::Output;
/// Returns the contained `Some` value, or logs at the warn level and computes a default value from a closure.
fn unwrap_or_else_log(self, f: impl FnOnce() -> Self::Output) -> Self::Output;
/// Returns the contained `Some` value, or logs at the warn level and returns the provided default.
fn unwrap_or_log(self, default: Self::Output) -> Self::Output;
}
/// Extension trait providing tracing alternatives to `Result` unwrap methods.
pub trait ResultExt {
/// The type of the "successful" output, intended to be `T` for a `Result<T, E>`.
type Output;
/// Returns the contained `Ok` value, or logs at the warn level and returns a default value.
fn unwrap_or_default_log(self) -> Self::Output;
/// Returns the contained `Ok` value, or logs at the warn level and computes a default value from a closure.
fn unwrap_or_else_log(self, f: impl FnOnce() -> Self::Output) -> Self::Output;
/// Returns the contained `Ok` value, or logs at the warn level and returns the provided default.
fn unwrap_or_log(self, default: Self::Output) -> Self::Output;
}
/// Like `ResultExt` for `Result<T, E>`, but doesn't require `E: Debug`.
///
/// This is provided for users who want to avoid logging sensitive information,
/// or who want to slim down their log files.
pub trait ResultExtNoDbg {
/// The type of the "successful" output, intended to be `T` for a `Result<T, E>`.
type Output;
/// Returns the contained `Ok` value, or logs at the warn level and returns a default value.
fn unwrap_or_default_log(self) -> Self::Output;
/// Returns the contained `Ok` value, or logs at the warn level and computes a default value from a closure.
fn unwrap_or_else_log(self, f: impl FnOnce() -> Self::Output) -> Self::Output;
/// Returns the contained `Ok` value, or logs at the warn level and returns the provided default.
fn unwrap_or_log(self, default: Self::Output) -> Self::Output;
}
impl<T: Default> OptionExt for Option<T> {
type Output = T;
#[track_caller]
fn unwrap_or_default_log(self) -> T {
if let Some(x) = self {
x
} else {
option_error();
T::default()
}
}
#[track_caller]
fn unwrap_or_else_log(self, f: impl FnOnce() -> T) -> T {
if let Some(x) = self {
x
} else {
option_error();
f()
}
}
#[track_caller]
fn unwrap_or_log(self, default: T) -> T {
if let Some(x) = self {
x
} else {
option_error();
default
}
}
}
impl<T: Default, E: core::fmt::Debug> ResultExt for Result<T, E> {
type Output = T;
#[track_caller]
fn unwrap_or_default_log(self) -> T {
match self {
Ok(x) => x,
Err(err) => {
result_error(&err);
T::default()
}
}
}
#[track_caller]
fn unwrap_or_else_log(self, f: impl FnOnce() -> T) -> T {
match self {
Ok(x) => x,
Err(err) => {
result_error(&err);
f()
}
}
}
#[track_caller]
fn unwrap_or_log(self, default: T) -> T {
match self {
Ok(x) => x,
Err(err) => {
result_error(&err);
default
}
}
}
}
impl<T: Default, E> ResultExtNoDbg for Result<T, E> {
type Output = T;
#[track_caller]
fn unwrap_or_default_log(self) -> T {
if let Ok(x) = self {
x
} else {
no_dbg_error();
T::default()
}
}
#[track_caller]
fn unwrap_or_else_log(self, f: impl FnOnce() -> T) -> T {
if let Ok(x) = self {
x
} else {
no_dbg_error();
f()
}
}
#[track_caller]
fn unwrap_or_log(self, default: T) -> T {
if let Ok(x) = self {
x
} else {
no_dbg_error();
default
}
}
}
#[cold]
#[inline(never)]
#[track_caller]
fn option_error() {
let caller = core::panic::Location::caller();
log::warn!("{caller} encountered `None`");
}
#[cold]
#[inline(never)]
#[track_caller]
fn result_error(err: &dyn core::fmt::Debug) {
let caller = core::panic::Location::caller();
log::warn!("{caller} encountered `Err({err:?})`");
}
#[cold]
#[inline(never)]
#[track_caller]
fn no_dbg_error() {
let caller = core::panic::Location::caller();
log::warn!("{caller} encountered `Err(_)`");
}