cause

[Cause] is a tiny generic implementation of the [std::error::Error] trait.

It takes 1 type parameter(T: Debug) who describes what error type happened.

It is dereferencable as &T.

And if you use macro [cause], it automatically stores some extra information, the filename and line number, only when it was compiled with debug_assertions.

Examples

```rust

[derive(Debug, PartialEq, Eq)]

pub enum ErrorType { InvalidArgumentsError, InternalError, NotFoundError, }

use ErrorType::*; use cause::Cause; use std::error::Error;

// It creates an instance of Cause<ErrorType> let cause = Cause::new(InternalError); asserteq!(cause.tostring(), "InternalError".tostring()); assert!(cause.message().isnone()); assert!(cause.source().is_none());

// It is dereferencable. assert_eq!(*cause, InternalError);

let httpstatuscode = match *cause { InternalError => 500, InvalidArgumentsError => 400, NotFoundError => 404, }; asserteq!(httpstatus_code, 500);

// set the message: let cause = Cause::new(InvalidArgumentsError).msg("oops!"); asserteq!(cause.tostring(), "InvalidArgumentsError: oops!".tostring()); asserteq!(cause.message(), Some(&"oops!".tostring())); assert!(cause.source().isnone());

// set the source of this error (any error type can be set with src()): let cause = Cause::new(InternalError).src(Cause::new(NotFoundError)); asserteq!( cause.tostring(), "InternalError\n\nCaused by:\n NotFoundError\n".tostring() ); assert!(cause.message().isnone()); assert!(cause.source().is_some());

// an example of Cause who have a standard io error. use std::io::Error as IoErr; use std::io::ErrorKind; let ioerr = IoErr::new(ErrorKind::Other, "oh no!"); println!("{}", Cause::new(InternalError).src(ioerr).msg("internal error caused by io error"));

// a couple of macro examples use cause::cause;

let cause = cause!(InternalError); println!("{}", cause); // => "InternalError" on release build // => "InternalError: [lib.rs:64]" on debug build

let cause = cause!(NotFoundError, "There is no such contents."); println!("{}", cause); // => "InternalError: There is no such contents." on release build // => "InternalError: There is no such contents. [lib.rs:69]" on debug build

```

Changelog

0.1.2

Fixed cause macro issue that use cause::Cause was implicitly required,

0.1.1

Following getter methods are added to [Cuase].

Cause::message()
Cuase::cause()

0.1.0

Initial Version

License

The MIT License (MIT)