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elaborate error macro and apply at various callsites

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Signed-off-by: Jason Volk <jason@zemos.net>
This commit is contained in:
Jason Volk 2024-07-13 21:11:05 +00:00
parent b3f2288d07
commit 05efd9b044
23 changed files with 161 additions and 140 deletions
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103
src/core/error/err.rs
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@ -1,3 +1,36 @@
//! Error construction macros
//!
//! These are specialized macros specific to this project's patterns for
//! throwing Errors; they make Error construction succinct and reduce clutter.
//! They are developed from folding existing patterns into the macro while
//! fixing several anti-patterns in the codebase.
//!
//! - The primary macros `Err!` and `err!` are provided. `Err!` simply wraps
//! `err!` in the Result variant to reduce `Err(err!(...))` boilerplate, thus
//! `err!` can be used in any case.
//!
//! 1. The macro makes the general Error construction easy: `return
//! Err!("something went wrong")` replaces the prior `return
//! Err(Error::Err("something went wrong".to_owned()))`.
//!
//! 2. The macro integrates format strings automatically: `return
//! Err!("something bad: {msg}")` replaces the prior `return
//! Err(Error::Err(format!("something bad: {msg}")))`.
//!
//! 3. The macro scopes variants of Error: `return Err!(Database("problem with
//! bad database."))` replaces the prior `return Err(Error::Database("problem
//! with bad database."))`.
//!
//! 4. The macro matches and scopes some special-case sub-variants, for example
//! with ruma ErrorKind: `return Err!(Request(MissingToken("you must provide
//! an access token")))`.
//!
//! 5. The macro fixes the anti-pattern of repeating messages in an error! log
//! and then again in an Error construction, often slightly different due to
//! the Error variant not supporting a format string. Instead `return
//! Err(Database(error!("problem with db: {msg}")))` logs the error at the
//! callsite and then returns the error with the same string. Caller has the
//! option of replacing `error!` with `debug_error!`.
#[macro_export]
macro_rules! Err {
($($args:tt)*) => {
@ -7,36 +40,56 @@ macro_rules! Err {
#[macro_export]
macro_rules! err {
(error!($($args:tt),+)) => {{
$crate::error!($($args),+);
$crate::error::Error::Err(std::format!($($args),+))
(Config($item:literal, $($args:expr),*)) => {{
$crate::error!(config = %$item, $($args),*);
$crate::error::Error::Config($item, $crate::format_maybe!($($args),*))
}};
(debug_error!($($args:tt),+)) => {{
$crate::debug_error!($($args),+);
$crate::error::Error::Err(std::format!($($args),+))
(Request(Forbidden($level:ident!($($args:expr),*)))) => {{
$crate::$level!($($args),*);
$crate::error::Error::Request(
::ruma::api::client::error::ErrorKind::forbidden(),
$crate::format_maybe!($($args),*)
)
}};
($variant:ident(error!($($args:tt),+))) => {{
$crate::error!($($args),+);
$crate::error::Error::$variant(std::format!($($args),+))
}};
($variant:ident(debug_error!($($args:tt),+))) => {{
$crate::debug_error!($($args),+);
$crate::error::Error::$variant(std::format!($($args),+))
}};
(Config($item:literal, $($args:tt),+)) => {{
$crate::error!(config = %$item, $($args),+);
$crate::error::Error::Config($item, std::format!($($args),+))
}};
($variant:ident($($args:tt),+)) => {
$crate::error::Error::$variant(std::format!($($args),+))
(Request(Forbidden($($args:expr),*))) => {
$crate::error::Error::Request(
::ruma::api::client::error::ErrorKind::forbidden(),
$crate::format_maybe!($($args),*)
)
};
($string:literal$(,)? $($args:tt),*) => {
$crate::error::Error::Err(std::format!($string, $($args),*))
(Request($variant:ident($level:ident!($($args:expr),*)))) => {{
$crate::$level!($($args),*);
$crate::error::Error::Request(
::ruma::api::client::error::ErrorKind::$variant,
$crate::format_maybe!($($args),*)
)
}};
(Request($variant:ident($($args:expr),*))) => {
$crate::error::Error::Request(
::ruma::api::client::error::ErrorKind::$variant,
$crate::format_maybe!($($args),*)
)
};
($variant:ident($level:ident!($($args:expr),*))) => {{
$crate::$level!($($args),*);
$crate::error::Error::$variant($crate::format_maybe!($($args),*))
}};
($variant:ident($($args:expr),*)) => {
$crate::error::Error::$variant($crate::format_maybe!($($args),*))
};
($level:ident!($($args:expr),*)) => {{
$crate::$level!($($args),*);
$crate::error::Error::Err($crate::format_maybe!($($args),*))
}};
($($args:expr),*) => {
$crate::error::Error::Err($crate::format_maybe!($($args),*))
};
}