diff --git a/src/doc/book/error-handling.md b/src/doc/book/error-handling.md index d94eeaebf4021..544f837d69b26 100644 --- a/src/doc/book/error-handling.md +++ b/src/doc/book/error-handling.md @@ -1829,7 +1829,7 @@ use std::error::Error; fn search> (file_path: P, city: &str) - -> Result, Box> { + -> Result, Box> { let mut found = vec![]; let file = try!(File::open(file_path)); let mut rdr = csv::Reader::from_reader(file); @@ -1858,20 +1858,17 @@ Instead of `x.unwrap()`, we now have `try!(x)`. Since our function returns a `Result`, the `try!` macro will return early from the function if an error occurs. -There is one big gotcha in this code: we used `Box` -instead of `Box`. We did this so we could convert a plain string to an -error type. We need these extra bounds so that we can use the -[corresponding `From` -impls](../std/convert/trait.From.html): +At the end of `search` we also convert a plain string to an error type +by using the [corresponding `From` impls](../std/convert/trait.From.html): ```rust,ignore // We are making use of this impl in the code above, since we call `From::from` // on a `&'static str`. -impl<'a, 'b> From<&'b str> for Box +impl<'a> From<&'a str> for Box // But this is also useful when you need to allocate a new string for an // error message, usually with `format!`. -impl From for Box +impl From for Box ``` Since `search` now returns a `Result`, `main` should use case analysis @@ -1964,7 +1961,7 @@ use std::io; fn search> (file_path: &Option

, city: &str) - -> Result, Box> { + -> Result, Box> { let mut found = vec![]; let input: Box = match *file_path { None => Box::new(io::stdin()), @@ -2175,9 +2172,8 @@ heuristics! `unwrap`. Be warned: if it winds up in someone else's hands, don't be surprised if they are agitated by poor error messages! * If you're writing a quick 'n' dirty program and feel ashamed about panicking - anyway, then use either a `String` or a `Box` for your - error type (the `Box` type is because of the - [available `From` impls](../std/convert/trait.From.html)). + anyway, then use either a `String` or a `Box` for your + error type. * Otherwise, in a program, define your own error types with appropriate [`From`](../std/convert/trait.From.html) and