Best approach for aliases namespace from config

Question

I'm working on a library that contains a large number of components that have namespaces that are nested. Also, when a new module inside the library get's added, we then have to add the namespace and sometimes this namespaces can change and then it becomes hellish to maintain.

I have been thinking of a solution or approach to solving this problem and come up with this idea:

The optimal approach would be to have a .h file containing the all of the namespaces:

namespace Config {

     namespace PCA = LibraryName::Statistical::Components::PCA; 
}

And then I can include this config file into the main entry to the application..

But, how I get to this point is what I am having trouble getting to. So here is my thought process:

If I create a "pre-compiled" Config.h that contains something like (Syntax is not right, but I would parse this)

namespace Config {

     "aliases" = [

         "PCA" =>  "LibraryName::Statistical::Components::PCA"
      ];
}

Then, some way inside the Makefile parse this syntax, and generate a .h file, with the aliases inside it and then this would work.. But I don't know if this is possible with a Makefile?

The second approach, would be to create a shell command, on the lines of: build_config which then parses this config file and then generate the .h to be used in the entry to the program?

Alternatively, I can use JSON and then parse the JSON using any of the above..

Can anyone give me any guidance to which approach would be better for this, also, is this just causing unnecessary problems?

ALSO: A series of clients / Users have also asked for the ability to change the namespace aliases..

Answer 1

This is a classic XY problem. You have problem X, which is causing problem Y, so you're asking for the solution to problem Y. But the best way of solving problem Y is to solve problem X.

You're asking about generating namespace alias configuration files (Y). But your real problem (X) is that your namespacing is way too complex! C++'s namespaces are not intended to be deeply nested or particularly long. They're intended to be short and not deeply nested. Generally a single namespace is all that is required for a small to medium-sized library, and even large libraries if well-designed can sit in a single namespace.

Nearly all of the C++ standard library, not a small library at all, is in std. There's also std::chrono and a couple of other specialised namespaces, but we don't use std::containers::vector or std::algorithms::sorting::stable_sort, we use std::vector and std::stable_sort.

Simplify the namespacing and you won't need to generate a namespace alias configuration file or anything silly like that.