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//! Some macros to help with dynamic error handling/logging. //! //! The goal of this crate is to unify all error types without compromising type safety. //! //! The main features of this crate are the `dynerr!` and `dynmatch!` macros. when used alongside the return type `DynResult<T>`, they allows you to return multiple error types from a function then easily match for them during your error handling. Using dynerr, theres no need to ever wrap errors. use std::fmt; use std::path::Path; use std::fs::{OpenOptions, remove_file}; use std::io::prelude::*; ///type alias for an error returned by `dynerr!` and `DynResult<T>` pub type DynError = Box<dyn std::error::Error>; /// An alias for result that uses DynError /// ///# Example /// ```rust ///# use dynerr::*; ///# use std::{fmt, error}; ///# ///# ///a custom error type ///# #[derive(Debug)] ///# enum ExampleError1 { ///# ThisError(u32), ///# } ///# //impl display formatting for error ///# impl fmt::Display for ExampleError1 { ///# fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { ///# match self { ///# ExampleError1::ThisError(i) => write!(f, "ExampleError1::ThisError: {}",i), ///# } ///# } ///# } ///# //impl error conversion for error ///# impl error::Error for ExampleError1 {} ///# /// fn try_something(x: u32) -> DynResult<u32> { /// if x > 10 {Ok(x)} /// else if x < 5 {dynerr!(ExampleError1::ThisError(x))} /// else { /// std::fs::File::open("none")?; /// Ok(x) /// } /// } ///# ///# fn main() { ///# try_something(11); ///# } /// ``` pub type DynResult<T> = std::result::Result<T, DynError>; /// A macro for returning custom errors as DynError. /// ///# Example /// /// ```rust ///# use dynerr::*; ///# use std::{fmt, error}; ///# ///# //THIS SECTION IS CREATING THE FIRST CUSTOM ERROR ///# ///a custom error type ///# #[derive(Debug)] ///# enum ExampleError1 { ///# ThisError(u32), ///# } ///# //impl display formatting for error ///# impl fmt::Display for ExampleError1 { ///# fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { ///# match self { ///# ExampleError1::ThisError(i) => write!(f, "ExampleError1::ThisError: {}",i), ///# } ///# } ///# } ///# //impl error conversion for error ///# impl error::Error for ExampleError1 {} ///# ///# //THIS SECTION IS CREATING THE SECOND CUSTOM ERROR ///# #[derive(Debug)] ///# enum ExampleError2 { ///# ThatError(u32), ///# } ///# impl fmt::Display for ExampleError2 { ///# fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { ///# match self { ///# ExampleError2::ThatError(i) => write!(f, "ExampleError2::ThatError: {}",i), ///# } ///# } ///# } ///# impl error::Error for ExampleError2 {} ///# ///# ///# ///THIS SECTION IS USING IT ///# ///# ///shows error handling capabilities using DynError /// fn example(x: u32) -> DynResult<u32> { /// match x { /// 1 => Ok(x), //Ok /// 2..=4 => dynerr!(ExampleError1::ThisError(x)), //custom error /// 5..=10 => dynerr!(ExampleError2::ThatError(x)), //different custom error /// _ => { /// std::fs::File::open("none")?; //an error not even defined by you! /// Ok(x) /// } /// } /// } ///# ///# fn main() { ///# example(3); ///# } /// ``` #[macro_export] macro_rules! dynerr { ($e:expr) => {return Err(Box::new($e))}; } /// Performs a dynamic match operation on multiple error types. /// /// types must be specified beforehand with the "type" keyword.\ /// match arms (excluding the final exhaustive arm) must be specified with the "arm" keyword. /// ///# Example /// ```rust ///# use dynerr::*; ///# use std::{fmt, error}; ///# ///# //THIS SECTION IS CREATING THE FIRST CUSTOM ERROR ///# ///a custom error type ///# #[derive(Debug)] ///# enum ExampleError1 { ///# ThisError(u32), ///# } ///# //impl display formatting for error ///# impl fmt::Display for ExampleError1 { ///# fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { ///# match self { ///# ExampleError1::ThisError(i) => write!(f, "ExampleError1::ThisError: {}",i), ///# } ///# } ///# } ///# //impl error conversion for error ///# impl error::Error for ExampleError1 {} ///# ///# //THIS SECTION IS CREATING THE SECOND CUSTOM ERROR ///# #[derive(Debug)] ///# enum ExampleError2 { ///# ThatError(u32), ///# } ///# impl fmt::Display for ExampleError2 { ///# fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { ///# match self { ///# ExampleError2::ThatError(i) => write!(f, "ExampleError2::ThatError: {}",i), ///# } ///# } ///# } ///# impl error::Error for ExampleError2 {} ///# ///# ///# ///THIS SECTION IS USING IT ///# ///# ///shows error handling capabilities using DynError ///# fn example(x: u32) -> DynResult<u32> { ///# match x { ///# 1 => Ok(x), //Ok ///# 2..=4 => dynerr!(ExampleError1::ThisError(x)), //custom error ///# 5..=10 => dynerr!(ExampleError2::ThatError(x)), //different custom error ///# _ => { ///# std::fs::File::open("none")?; //an error not even defined by you! ///# Ok(x) ///# } ///# } ///# } ///# ///# fn main() { /// let _i = match example(20) { /// Ok(i) => i, /// Err(e) => { /// dynmatch!(e, //the DynError to be matched /// type ExampleError1 { //an error type /// arm ExampleError1::ThisError(2) => logged_panic!("it was 2!"), //arm [pattern] => {code} /// _ => panic!("{}",e) //_ => {code} /// }, /// type ExampleError2 { /// arm ExampleError2::ThatError(8) => logged_panic!("it was 8!", "test.log"), /// arm ExampleError2::ThatError(9) => 9, /// _ => panic!("{}",e) /// }, /// type std::io::Error { //an error type not defined by you /// arm i if i.kind() == std::io::ErrorKind::NotFound => 5, //a match guard included in the match /// _ => panic!("{}", e) /// }, /// _ => panic!("{}",e) //what to do if error type isn't found /// ) /// } /// }; ///# } /// ``` #[macro_export] macro_rules! dynmatch { ($e:expr, $(type $ty:ty {$(arm $( $pattern:pat )|+ $( if $guard: expr )? => $result:expr),*, _ => $any:expr}),*, _ => $end:expr) => ( $( if let Some(e) = $e.downcast_ref::<$ty>() { match e { $( $( $pattern )|+ $( if $guard )? => {$result} )* _ => $any } } else )* {$end} ); } ///deletes the supplied file pub fn clean_log(log_file: &str) { if Path::new(log_file).exists() { remove_file(log_file).unwrap_or_else(|e| panic!("Dynerr: Error cleaning file: {}", e)) } } /// deletes the supplied log file. /// /// if no file supplied defaults to "event.log". /// /// #Example /// ``` ///# use dynerr::*; ///# fn main() { /// log!("hello world", "my.log"); /// clean!("my.log"); /// log!("i just cleaned my.log"); /// clean!(); ///# } /// ``` #[macro_export] macro_rules! clean { () => { $crate::clean_log("event.log") }; ($log:expr) => { $crate::clean_log($log) }; } /// Appends [event] to [log_file]. /// /// creates the file if it doesnt exist.\ /// panics on failure to create or appending to file.\ /// not meant to be used on its own. use logging macros instead pub fn log<T: fmt::Display>(event: T, log_file: &str) -> T { let mut file = OpenOptions::new() .append(true) .create(true) .open(log_file) .unwrap_or_else(|e| panic!("Dynerr: Error opening log during crash: {} (error passed to logger was: {})",e,event)); file.write_all(format!("{}\n",event.to_string()).as_bytes()) .unwrap_or_else(|e| panic!("Dynerr: Error appending to log during crash: {} (error passed to logger was: {})",e,event)); event } /// Appends [event] to [file]. /// /// If no file supplied then defaults to "event.log".\ /// creates the file if it doesnt exist. /// /// ///# Example /// /// ```rust ///# use dynerr::*; ///# fn main() { /// log!("this is a test", "test.log"); /// log!("do log!"); ///# } /// ``` #[macro_export] macro_rules! log { ($event:expr) => { $crate::log($event, "event.log") }; ($event:expr, $log:expr) => { $crate::log($event, $log) }; } /// Appends [event] to [file] then panics. /// /// If no file supplied then defaults to "event.log".\ /// creates the file if it doesnt exist. /// ///# Example /// /// ```rust ///# use dynerr::*; ///# fn main() { ///# if false { /// logged_panic!("Hi!", "test.log"); /// logged_panic!("default log"); ///# } ///# } /// ``` #[macro_export] macro_rules! logged_panic { ($e: expr) => { panic!("{}",log!($e)); }; ($e: expr, $log:expr) => { panic!("{}",log!($e, $log)); } } /// Shortcut for .unwrap_or_else(|e| logged_panic!(e)) for DynResult. /// /// If no file supplied then defaults to "event.log".\ /// creates the file if it doesnt exist. /// ///# Example /// /// ```rust ///# use dynerr::*; ///# ///shows error handling capabilities using DynError ///# fn try_something() -> DynResult<()> { ///# Ok(()) ///# } ///# ///# fn main() { /// let i = check!(try_something()); /// let i = check!(try_something(), "test.log"); ///# } /// ``` #[macro_export] macro_rules! check { ($x:expr) => { $x.unwrap_or_else(|e| logged_panic!(e)) }; ($x:expr, $log:expr) => { $x.unwrap_or_else(|e| logged_panic!(e, $log)) }; } ///an example #[cfg(test)] mod tests { use super::*; //THIS SECTION IS CREATING THE FIRST CUSTOM ERROR use std::{fmt, error}; ///a custom error type #[derive(Debug)] enum ExampleError1 { ThisError(u32), } //impl display formatting for error impl fmt::Display for ExampleError1 { fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { match self { ExampleError1::ThisError(i) => write!(f, "ExampleError1::ThisError: {}",i), } } } //impl error conversion for error impl error::Error for ExampleError1 {} //THIS SECTION IS CREATING THE SECOND CUSTOM ERROR #[derive(Debug)] enum ExampleError2 { ThatError(u32), } impl fmt::Display for ExampleError2 { fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { match self { ExampleError2::ThatError(i) => write!(f, "ExampleError2::ThatError: {}",i), } } } impl error::Error for ExampleError2 {} ///shows error handling capabilities using DynError fn example(x: u32) -> DynResult<u32> { match x { 1 => Ok(x), //Ok 2..=4 => dynerr!(ExampleError1::ThisError(x)), //custom error 5..=10 => dynerr!(ExampleError2::ThatError(x)), //different custom error _ => { std::fs::File::open("none")?; //an error not even defined by you! Ok(x) } } } ///THIS SECTION IS USING IT #[test] pub fn test() -> DynResult<()> { log!("this is a test", "test.log"); let _i = match example(20) { Ok(i) => i, Err(e) => { dynmatch!(e, //the DynError to be matched type ExampleError1 { //an error group arm ExampleError1::ThisError(2) => logged_panic!("it was 2!"), //arm [pattern] => {code} _ => panic!("{}",e) //_ => {code} }, type ExampleError2 { arm ExampleError2::ThatError(8) => logged_panic!("it was 8!", "test.log"), arm ExampleError2::ThatError(9..=11) => 10, _ => panic!("{}",e) }, type std::io::Error { //an error type not defined by you arm i if i.kind() == std::io::ErrorKind::NotFound => 5, //a match guard included in the match _ => panic!("{}", e) }, _ => panic!("{}",e) //what to do if error group isn't found ) } }; log!("do logged_panic! if error"); let _i = check!(example(1)); let _i = check!(example(1), "test.log"); Ok(()) } }