deal.II currently only requires a C++14-conforming compiler, but there are a number of functions and classes from the C++17 standard that are easy to provide also in case the compiler only supports C++14. These are collected in the current namespace.
The most notable example is the std::optional class that was introduced to C++ starting with the C++17 standard.
There are other small additions in this namespace that allow us to use C++17 features at this point already, even though we don't require a C++17-compliant compiler.
- Note
- If the compiler in use actually does support C++17, then the contents of this namespace are simply imported classes and functions from namespace
std. That is, we fall back to what the compiler provides, rather than our own implementations.
1.9.5