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| -rw-r--r-- | src/doc/trpl/documentation.md | 30 |
1 files changed, 30 insertions, 0 deletions
diff --git a/src/doc/trpl/documentation.md b/src/doc/trpl/documentation.md index e101d4bc0d4..dc91c90b0fd 100644 --- a/src/doc/trpl/documentation.md +++ b/src/doc/trpl/documentation.md @@ -373,6 +373,36 @@ we can add the `#[macro_use]` attribute. Second, we’ll need to add our own `main()` as well. Finally, a judicious use of `#` to comment out those two things, so they don’t show up in the output. +Another case where the use of `#` is handy is when you want to ignore +error handling. Lets say you want the following, + +```rust,ignore +/// use std::io; +/// let mut input = String::new(); +/// try!(io::stdin().read_line(&mut input)); +``` + +The problem is that `try!` returns a `Result<T, E>` and test functions +don't return anything so this will give a mismatched types error. + +```rust,ignore +/// A doc test using try! +/// +/// ``` +/// use std::io; +/// # fn foo() -> io::Result<()> { +/// let mut input = String::new(); +/// try!(io::stdin().read_line(&mut input)); +/// # Ok(()) +/// # } +/// ``` +# fn foo() {} +``` + +You can get around this by wrapping the code in a function. This catches +and swallows the `Result<T, E>` when running tests on the docs. This +pattern appears regularly in the standard library. + ### Running documentation tests To run the tests, either: |