diff options
Diffstat (limited to 'exercises/error_handling/errorsn.rs')
| -rw-r--r-- | exercises/error_handling/errorsn.rs | 137 |
1 files changed, 1 insertions, 136 deletions
diff --git a/exercises/error_handling/errorsn.rs b/exercises/error_handling/errorsn.rs index c2b16ce..2f3566b 100644 --- a/exercises/error_handling/errorsn.rs +++ b/exercises/error_handling/errorsn.rs @@ -13,7 +13,7 @@ // type goes where the question marks are, and how do we return // that type from the body of read_and_validate? // -// Scroll down for hints :) +// Execute `rustlings hint errors4` for hints :) use std::error; use std::fmt; @@ -110,138 +110,3 @@ impl error::Error for CreationError { } } } - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -// First hint: To figure out what type should go where the ??? is, take a look -// at the test helper function `test_with_str`, since it returns whatever -// `read_and_validate` returns and`test_with_str` has its signature fully -// specified. - - - - - - - - - - - - - - - - - - - - -// Next hint: There are three places in `read_and_validate` that we call a -// function that returns a `Result` (that is, the functions might fail). -// Apply the `?` operator on those calls so that we return immediately from -// `read_and_validate` if those function calls fail. - - - - - - - - - - - - - - - - - - - - -// Another hint: under the hood, the `?` operator calls `From::from` -// on the error value to convert it to a boxed trait object, a Box<dyn error::Error>, -// which is polymorphic-- that means that lots of different kinds of errors -// can be returned from the same function because all errors act the same -// since they all implement the `error::Error` trait. -// Check out this section of the book: -// https://doc.rust-lang.org/book/ch09-02-recoverable-errors-with-result.html#a-shortcut-for-propagating-errors-the--operator - - - - - - - - - - - - - - - - - - - - -// Another another hint: Note that because the `?` operator returns -// the *unwrapped* value in the `Ok` case, if we want to return a `Result` from -// `read_and_validate` for *its* success case, we'll have to rewrap a value -// that we got from the return value of a `?`ed call in an `Ok`-- this will -// look like `Ok(something)`. - - - - - - - - - - - - - - - - - - - - -// Another another another hint: `Result`s must be "used", that is, you'll -// get a warning if you don't handle a `Result` that you get in your -// function. Read more about that in the `std::result` module docs: -// https://doc.rust-lang.org/std/result/#results-must-be-used |
