mp11 | C++11 | SDK library

This is probably a weird use case, but I am trying to hack around the fact string literals can not be used as arguments to templates using std::array as non template type parameter.

This works but with extreme limitation that all strings must be of same length(I could use MAX_STR_LEN=100 or whatever and make all arrays that size, but that feels ugly...).

Is there a way to make this code work so that different size std::arrays can be accepted as template parameter?

I have the following code where I implement dispatching on runtime value to interpret the data in certain way(in this toy example data can be either uint8_t or short).

Code seems to work, but I am wondering if I can somehow microoptimize the code so that when I have a hit(processing function matches) processing is stopped (currently even if first element of tuple is a "handler" entire tuple is iterated over at runtime).

For a better understanding and learning, I tried to use the boost mp11 library to implement the Dimensional Analysis from "C++ Template Metaprogramming" book (also found in the documentation of boost mpl library). A reason why was that C++11 has features that weren't available when the book was written, features that are very useful now.

I am using Visual Studio 2019, community version.

All went well until I had to implement the operator*. I couldn't perform the trick that was used for the mpl library. Operator+ worked well, so the problem must be similar to the one pointed out in the book, but should have a different solution. Please, help me to find it.

The (shortest possible) example code is below. It gets compiled and runs correctly. When the last 3 lines are uncommented, one gets the error:

error C2676: binary '*': 'quantity' does not define this operator or a conversion to a type acceptable to the predefined operator

For some reason, operator* is invisible, while similar operator+ is.

Thank you

I am trying to learn basics of boost::mp11, docs are ok, but one thing I do not understand is the following: what is the purpose of quoted metafunctions? Docs say this:

A quoted metafunction is a class with a public metafunction member called fn, for example

I wonder why the following code does not work as expected(is_numeric is always 0).

I have 2 tables, tableStock and tableParts:

In C++, I'm trying to write something similar to boost-mp11's mp_for_each. However, whilst mp_for_each always calls the supplied function for every T in the given mp_list, I'm trying to come up with a solution that stops traversal once a run-time call to the function yields a value evaluating to false in an if-statement.

See the implementation of mp_for_each and a usage example:

Implementation on GitHub

Usage example in Boost reference manual

Apparently, the implementation of mp_for_each manages to pass the function argument as a constant expression, thus enabling the user to apply it where a constant expression is required. Whilst I took a different approach incorporating template tail recursion, I expected the function argument to be passed as a constant expression as welll. However, GCC complains that it "is not a constant expression".

My code looks like this:

The following command builds boost using VCPKG.