nalydmerc/rustlings
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

feat: Refactor hint system

Browse Source 
Hints are now accessible using the CLI subcommand `rustlings hint
<exercise name`.

BREAKING CHANGE: This fundamentally changes the way people interact with exercises.
This commit is contained in:
marisa
2019-11-11 16:51:38 +01:00
parent 627cdc07d0
commit 9bdb0a12e4
47 changed files with 400 additions and 1681 deletions
Download Patch File Download Diff File Expand all files Collapse all files

137
exercises/error_handling/errorsn.rs
View File

@@ -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