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use std::error; use std::fmt::{self, Formatter, Display}; use std::result; #[derive(Debug)] pub struct Error{ description: String, cause: Option<Box<dyn error::Error + Send + Sync>>, } impl Error{ pub fn new(desc: &str) -> Error{ Error{ description: desc.to_owned(), cause: None, } } pub fn with_cause<'a, E: 'static + error::Error + Send + Sync, C: Into<Option<E>>>(desc: &str, cause: C) -> Error{ Error{ description: desc.to_owned(), cause: cause.into().map(|e| Box::new(e) as Box<dyn error::Error + Send + Sync>), } } } impl error::Error for Error{ fn source(&self) -> Option<&(dyn error::Error + 'static)>{ self.cause.as_ref().map(|e| &**e as &dyn error::Error) } } impl Display for Error{ fn fmt(&self, fmt: &mut Formatter) -> fmt::Result{ fmt.write_str(&self.description)?; fmt.write_str("\n")?; if let Some(cause) = self.cause.as_ref(){ fmt.write_str("cause: ")?; cause.fmt(fmt) }else{ Ok(()) } } } impl<'a> From<&'a str> for Error{ fn from(desc: &str) -> Error{ Error::new(desc) } } pub type Result<T> = result::Result<T, Error>; pub trait LogErr{ fn log_err(self, desc: &str) -> Self; } impl<T,E: error::Error> LogErr for result::Result<T,E>{ fn log_err(self, desc: &str) -> Self{ self.map_err(|err| { log::error!("{}: {}", desc, err); err }) } }