Meeting 3 August 2017
Toronto trip report by Andrew Pardoe (MSFT)
- Biggest news: Concepts TS merged into C++ draft standard
- EWG is committed to bringing back an abbreviated syntax in future meetings, ideally before C++20 is finished. P0694R0 is a paper by Bjarne Stroustrup on the natural syntax.
- Modules TS discussions in detail
- Other proposals described in detail
- Discouraged proposals
Toronto trip report by Botond Ballo
- Reddit thread
- Detailed EWG report
- Rejected proposals
- Detailed report on Concepts TS
AFTs have been controversial since their introduction, due to their ability to make template code look like non-template code. Many have argued that this is a bad idea, beacuse template code is fundamentally different from non-template code (e.g. consider different name lookup rules, the need for syntactic disambiguators like typename, and the ability to define a function out of line). Others have argued that making generic programming (programming with templates) look more like regular programming is a good thing.
I really don’t understand this desire for a syntactic marker. IDEs are perfectly capable of semantic highlighting #
I don’t think it’s really so important to recognize templates that they need to be called out that way at all #
more than 30 years ago, when overloading was introduced in C++ there was a requirement of an overload declaration with the overload keyword. It didn’t work out #
I actually can’t remember if I have ever wanted to know whether a function is a template or not <…> You should not program in 2017 using 20 year old tools, nor should a language feature implemented in 2017 be designed with 20 year old tools in mind. #
<…> not everyone uses editors with semantic highlighting capabilities, and that people often look at code in non-editor contexts like code review tools
The language should not accumulate cruft to accommodate 10 year old tools #
What should the C++ Standards Committee be doing?
- Compile-time stability: Every change in behavior in a new version of the standard is detectable by a compiler for the previous version.
- Link-time stability: ABI breakage is avoided except in very rare cases, which will be welldocumented and supported by a written rationale.
- Compiler performance stability: Changes will not imply significant added compile-time costs for existing code.
- Run-time Performance stability: Changes will not imply added run-time costs to existing code.
- Progress: Every revision of the standard will offer improved support for some significant programming activity or community.
- Simplicity: Every revision of the standard will offer some simplification of some significant programming activity.
- Timeliness: The next revision of the standard will be shipped on time according to a published schedule.
- Reddit thread
Precompiled header issues and recommendations
Andrew Pardoe et al., Microsoft
- Move to a newer compiler, use x64 compiler
- Multi-CPU systems: Failure to automatically increase the pagefile size (Windows bug)
/MPcompiler option (Details)
- Don’t use
#pragma hdrstop, use
Undocumented MSVC options for build timing
- Source: Going Native 35
Using Trompeloeil (Björn Fahller)
A mocking framework for modern C++ (C++14, single header)
- NDC Oslo, June 2017
- ACCU 2017, May 2017
- Sweden C++, September 2016
- GitHub (Boost licence)
- Cheatsheet (PDF)
cppcoro: a library of coroutine abstractions
The ‘cppcoro’ library provides a set of general-purpose primitives for making use of the coroutines TS proposal described in N4628.
- Coroutine types:
- Awaitable types:
- Schedulers and I/O: