Module augrim::error

Common set of basic errors used throughout the library.

The errors in this module are intended to be used by themselves or as part of a more complex error enum.

Examples

Returning an Error from a Function

A function may return an error such as InternalError by itself.

use std::fs;

use augrim::error::InternalError;

fn check_path(path: &str) -> Result<bool, InternalError> {
    let metadata = fs::metadata(path).map_err(|e| InternalError::from_source(Box::new(e)))?;
    Ok(metadata.is_file())
}

Constructing Complex Errors

Errors such as InternalError may be used to construct more complicated errors by defining an enum.

use std::error;
use std::fmt;
use std::fs;

use augrim::error::InternalError;

#[derive(Debug)]
enum MyError {
    InternalError(InternalError),
    MissingFilenameExtension,
}

impl error::Error for MyError {}

impl fmt::Display for MyError {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        match self {
            MyError::InternalError(e) => write!(f, "{}", e),
            MyError::MissingFilenameExtension => write!(f, "Missing filename extension"),
        }
    }
}

fn check_path(path: &str) -> Result<bool, MyError> {
    match !path.ends_with(".md") {
        true => Err(MyError::MissingFilenameExtension),
        false => {
            let metadata = fs::metadata(path).map_err(|e| MyError::InternalError(InternalError::from_source(Box::new(e))))?;
            Ok(metadata.is_file())
        }
    }
}

Structs

InternalError

An error which is returned for reasons internal to the function.