QtCS2024 Error handling: Difference between revisions

Latest revision as of 11:45, 6 September 2024

Volker Hilsheimer Note taker: Thiago

Intro: we already have too many attempts at this, going back at least as far back as 2017.

Volker's proposal:

use the C++17-compatible full implementation by Sy Brand at https://github.com/tartanllama/expected
- Licence: CC0 (QtC legal needs to confirm it's ok to use even for commercial, but Thiago thinks it is [but he isn't a lawyer])
- Includes things that even most of Standard Library implementations don't yet
import into Qt
use it internally

Should we use it in public API?

If we do, then we can't switch to std::expected (C++23) before at least Qt 7.0
It becomes part of our ABI
Shouldn't be named q23::expected because it conveys the wrong message
Do we need to use it in public API?
- No, we don't need it
- But it's very useful for that; the type is designed for use in interface boundaries
Suggestion:
- Use it internally first so we gain experience with its issues and how to use it
- Then, later, make it public to use it

Alternatives:

@@ Line 2: / Line 2: @@
 ==Session Owners==
+Volker Hilsheimer
+Note taker: Thiago
 ==Notes==
+Intro: we already have too many attempts at this, going back at least as far back as 2017.
+[[File:QtCS2024 Error Handling.pdf|alt=Proposal to use Sy Brand's std::expected implementation in Qt|center|thumb]]
+Volker's proposal:
+* use the C++17-compatible full implementation by Sy Brand at https://github.com/tartanllama/expected
+** Licence: CC0 (QtC legal needs to confirm it's ok to use even for commercial, but Thiago thinks it is [but he isn't a lawyer])
+** Includes things that even most of Standard Library implementations don't yet
+* import into Qt
+* use it internally
+Should we use it in public API?
+* If we do, then we can't switch to <tt>std::expected</tt> (C++23) before at least Qt 7.0
+* It becomes part of our ABI
+* Shouldn't be named <tt>q23::expected</tt> because it conveys the wrong message
+* Do we need to use it in public API?
+** No, we don't '''need''' it
+** But it's very useful for that; the type is designed for use in interface boundaries
+* Suggestion:
+** Use it internally ''first'' so we gain experience with its issues and how to use it
+** Then, later, make it public to use it
+Alternatives:
+* [https://www.boost.org/doc/libs/1_79_0/libs/leaf/doc/html/index.html Boost LEAF]
+* [https://www.boost.org/doc/libs/1_85_0/libs/outcome/doc/html/index.html Boost Outcome]
 [[Category:QtCS2024]]