chainerror/booksrc/tutorial6.md
2019-03-04 11:44:15 +01:00

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# Downcast the Errors
`std::error::Error` comes with some helper methods to get to the original object of the
`&(dyn Error + 'static)` returned by `.source()`.
~~~rust,ignore
pub fn downcast_ref<T: Error + 'static>(&self) -> Option<&T>
pub fn downcast_mut<T: Error + 'static>(&mut self) -> Option<&mut T>
~~~
This is how it looks like, when using those:
~~~rust
{{#include ../examples/tutorial6.rs}}
# #[allow(dead_code)]
# mod chainerror {
{{#includecomment ../src/lib.rs}}
# }
~~~