[ceph.git] / ceph / src / boost / libs / leaf / examples / print_file / readme.md

# Print File Example

This directory has several versions of the same simple program presented in the [Five Minute Introduction](https://boostorg.github.io/leaf/#introduction), each using a different error handling style:

## Using exception handling:

* [print_file_eh.cpp](./print_file_eh.cpp) throws on error, using an exception type hierarchy for classification of failures.

* [print_file_eh_error_tags.cpp](./print_file_eh_error_tags.cpp) throws `std::exception` on error, using a separate set of individual error types, rather than an exception type hierarchy, for classification of failures.

## Using a `result<T>` type:

* [print_file_result.cpp](./print_file_result.cpp) reports errors with `leaf::result<T>`, using an error code `enum` for classification of failures.

* [print_file_outcome_result.cpp](./print_file_outcome_result.cpp) is the same as the above, but using `outcome::result<T>`. This demonstrates the ability to transport arbitrary error objects through APIs that do not use `leaf::result<T>`.

* [print_file_result_error_tags.cpp](./print_file_result_error_tags.cpp) reports errors with `leaf::result<T>`, using a separate set of individual error types, rather than an error code `enum`, for classification of failures.
Commit	Line	Data
20effc67 TL	1	# Print File Example
	2
	3	This directory has several versions of the same simple program presented in the [Five Minute Introduction](https://boostorg.github.io/leaf/#introduction), each using a different error handling style:
	4
	5	## Using exception handling:
	6
	7	* [print_file_eh.cpp](./print_file_eh.cpp) throws on error, using an exception type hierarchy for classification of failures.
	8
	9	* [print_file_eh_error_tags.cpp](./print_file_eh_error_tags.cpp) throws `std::exception` on error, using a separate set of individual error types, rather than an exception type hierarchy, for classification of failures.
	10
	11	## Using a `result<T>` type:
	12
	13	* [print_file_result.cpp](./print_file_result.cpp) reports errors with `leaf::result<T>`, using an error code `enum` for classification of failures.
	14
	15	* [print_file_outcome_result.cpp](./print_file_outcome_result.cpp) is the same as the above, but using `outcome::result<T>`. This demonstrates the ability to transport arbitrary error objects through APIs that do not use `leaf::result<T>`.
	16
	17	* [print_file_result_error_tags.cpp](./print_file_result_error_tags.cpp) reports errors with `leaf::result<T>`, using a separate set of individual error types, rather than an error code `enum`, for classification of failures.