Proposal for adding C++ level to the meta/libraries.json

From: Edward Diener (eldiener_at_[hidden])
Date: 2020-09-21 17:37:19

Since we are reviewing Vinnie Falco's JSON library I thought that this 
would be a good time to present a proposal to add information to each 
Boost library's meta/libraries.json file regarding the level of C++ 
standard compliance for that library. This could then be added to each 
library's visual documentation so that end-users would instantly know 
the C++ standard level they would need to use in order to use a Boost 
library.

My proposal is to add 3 fields whose data would be the same as the 
cxxstd allowed values from Boost Build, using the first value of each 
choice ( currently 03, 11, 14, 17, 20 ).

standard = minimum C++ level for the library
extended = same functionality in the library as the minimum C++ level 
but with extended use given higher C++ levels
required = new functionality in the library above the minimum C++ level 
which requires given higher C++ levels

The 'standard' field would be a single value, while the 'extended' or 
'required' fields could be more than one comma separated value. If you 
don't like the names for 'standard', 'extended', or 'required' you can 
bikeshed the name, although I think the 'standard' name is pretty well 
apparent.

The idea is to provide this information in the meta/libraries.json field 
for each library, so that the end-user of the library can immediately 
know the usability of the library with appropriate C++ standard levels 
of compilation.

I realize that the line between the 'extended' and 'required' entries, 
as I have described them, could be blurred. The 'standard' field remains 
the most important. I have long felt that the end-user should not have 
to do any investigation, in code or in documentation, just to determine 
if a library is usable for his C++ standard level of compilation.