etl/docs/utilities/result.md
John Wellbelove 4a88884b39
Issue/add hugo support for documentation (#1449)
* Add ranges

* Initial Hugo setup

* Work in progress

* Added selection for local or remote site

* Updated to 'light' theme

* Changed to using Hextra Hugo theme

* Changed to using Hextra Hugo theme

* Changed to Hextra Hugo theme

* Change to Hextra Hugo theme

* Updated Hugo setup.

* Updated Hugo setup.

# Conflicts:
#	docs/releases/_index.md

* Work in progress

* Added new fonts

Added new documentation

* Latest documentation updates

* Latest documentation updates

# Conflicts:
#	docs/containers/array.md
#	docs/containers/array_view.md
#	docs/containers/array_wrapper.md
#	docs/containers/bip_buffer_spsc_atomic.md
#	docs/containers/bitset.md
#	docs/containers/indirect_vector.md
#	docs/containers/vector.md
#	docs/getting-started/compilers.md

* Added bloom_filter markdown doc

* Added more documentation

Updated CSS for light and dark modes

* Fixed some menus

Added mode documentation files

* Updated CSS rules

Added badges to home page
Added uniqur_ptr + pool tutorial

* Fixed formatting on the home page markdown

Modified light amd dark code formatting

* Updated unique_ptr-with-pool

* Added container and shared message tutorials

* Updates to documentation

* Added const_multimap

* Updated source-formatting.md

* Added initial raw text files form Web site editor

* Innore coverage build directory

* Exported raw text documentation files from the web site editor

* Hugo updates

* Added Hugo intalation and markdown descriptions

* More addition to the documentation

* Added closure.md and updates to delegate.md

* Added format.md

* Added documentation for etl::delegate_observable, etl::function, Base64 codec

* Added io_port documentation

* Added basic_format_spec

* Added documentation for string_stream and string utilities.

* Added more documentation

Updated the documentation CSS

* Added documentation for clocks, day, duration

* Added more documentation for chrono classes

Updated callouts

* More chrono documentation

* Completed chrono documentation

* Maths functions documentation

* Completed maths documentation

* Completed maths documentation

* Completed maths documentation

* Completed maths documentation

* Added multiple documentation files

* Added iterator.md

* Added debug_count.md and versions.md

* Added debug_count.md and versions.md

* Added more documentation

* More documentation

* Added some design pattern documentation

Modified some of the layout files
Modified the About documentation

* Converted more documentation pages

Modified the site CSS

* Added more documentation

Moced some documentation files to new directories

* Added more documentation

Tweaks to CSS

* Added callback_timer_deferred_locked documentation

* Added callback_timer_locked documentation

* More documentation updates

* More documentation updates

* More documentation updates

* New documentation files.

Harmonised file name format

* New documentation files.

* Multiple document updates

* Multiple document updates

* Final conversion of web pages

* Updates before PR

* Updates before PR

* Updates before PR

# Conflicts:
#	docs/blog/_index.md

* Final pre PR updates

* Updates to message framework documentation

* Renamed directory

* Fix spelling

* Added author and date to blog files

Moved documentation files merged from development

* Fixed 'Description' typo

* Fix typos

# Conflicts:
#	docs/IO/io_port.md
#	docs/containers/sets/const-multiset.md
#	docs/containers/sets/const-set.md
#	docs/maths/correlation.md
#	docs/maths/gamma.md

* Renamed two files to lower case

* Minor renaming

* Added author and date

* Updated callout on bresenham_line.md

Added support for showing the ETL version on the documentation first page, by copying the version.txt file as a hugo asset.
Updated the Python 'update_release.py' to copy 'version.txt'

* Replace space in filename with hyphen.

Added more information to hugo-commands.md

* Replace space in filename with hyphen.

Added more information to hugo-commands.md

# Conflicts:
#	docs/getting-started/view-the-docs-locally/hugo-commands.md

* Added a link to pseudo_moving_average.md

* Updated title pages for groups

* Fixed missing 404 for non-existent pages

* Fixed coordinate variable names in the 'Calculating the intersection' example

---------

Co-authored-by: Roland Reichwein <Roland.Reichwein@bmw.de>
Co-authored-by: John Wellbelove <john.wellbelove@etlcpp.com>
Co-authored-by: John Wellbelove <john.wellbelove@etlcpp.co.uk>
2026-06-06 13:12:44 +01:00

2.7 KiB

title
result

{{< callout type="info">}} Header: result.h
From: 20.17.0
Similar to: std::expected {{< /callout >}}

{{< callout type="warning">}} This class is deprecated.
Use etl::expected as a replacement. {{< /callout >}}

A generic result type for returning either a result or an error. Deprecated. Use etl::expected

result

template <typename TValue, typename TError>
class result

template <typename TError>
class result<void, TError>

Description
Specialisation for void result.


result() = delete;

Description
Cannot be default constructed.


result(const result& other)

Description
Copy constructor.


result(result&& other)

Description
Move constructor.


result(const TValue& value)

Description
Construct from a value.
Not valid for void specialisation.


result(TValue&& value)

Description
Move construct from a value.
Not valid for void specialisation.


result(const TError& err)

Description
Construct from error.


result(TError&& err)

Description
Move construct from error.


result& operator =(const result& other)

Description
Copy assign.


result& operator =(result&& other)

Description
Move assign.


result& operator =(const TValue& value)

Description
Copy assign from value.
Not valid for void specialisation.


result& operator =(TValue&& value)

Description
Move assign from value.
Not valid for void specialisation.


result& operator =(const TError& err)

Description
Copy assign from error.


result& operator =(TError&& err)

Description
Move assign from error.


bool is_value() const

Description
true if result contains a value.


bool is_error() const

Description
true if result contains an error.


const TValue& value() const

Description
Returns a const reference to the value.
Undefined if the result does not contain an value.
Not valid for void specialisation.


TValue&& value()

Description
Returns an rvalue reference to the value.
Undefined if the result does not contain an value.
Not valid for void specialisation.


const TError& error() const

Description
Returns a const reference to the error.
Undefined if the result does not contain an error.


TError&& error()

Description
Returns an rvalue reference to the error.
Undefined if the result does not contain an error.