Re: [Pyfltk-user] How do I wrap fltk1.5's new Fl:: namespace which is no longer a struct?

[Matthias M. <mm...@ma...>]

Static class members, the way Fl used to be, and namespace members, as it is now, are almmost the same thing in C++. They are global variables and global functions that have an additional name component, Fl::. 


IIRC you are using pybind, which support C++11, so it should support namespaces as well.

I found a few issue reports on this, https://github.com/pybind/pybind11/issues/968 from 2017 for example, so I assume that this is a known factor, and pybind offers a solution.

There are no "unnamed namespaces", so everything should be straight forward.

If you like, I can take a deeper dive into pybind and try to find out what commands they need to generate the bindings.


Here is ChatGPTs opinion with the usual cautions about AI:




pybind11 does recognize C++ namespaces — but only if you tell it.
It does not discover namespaces automatically.
You need to explicitly create the module hierarchy that corresponds to your C++ namespace hierarchy.
Here is the rule:
✅ pybind11 mirrors C++ namespaces only when you create submodules manually📌 Example: C++ namespace you want to exposenamespace fltk {
int version = 10403;

void beep() { /* ... */ }

namespace detail {
void log(const char* msg) { /* ... */ }
}
}

📌 pybind11 bindings — how to expose namespaces#include <pybind11/pybind11.h>

namespace py = pybind11;

PYBIND11_MODULE(fltk, m) {
m.attr("version") = fltk::version;
m.def("beep", &fltk::beep);

// Create a submodule that mirrors namespace fltk::detail
py::module_ detail = m.def_submodule("detail", "FLTK internal utilities");
detail.def("log", &fltk::detail::log);
}

🔍 What this produces in Pythonimport fltk

print(fltk.version)
fltk.beep()

fltk.detail.log("hello")

❗ Important: pybind11 will NOT detect namespaces for you
    • It does not parse C++ headers
    • It does not traverse namespaces
    • It does not autogenerate submodules
You must create the module/submodule mirror yourself.🧩 How pybind11 maps to namespaces
C++ construct pybind11 equivalentnamespace X py::module_ X = m.def_submodule("X")
free function m.def("name", &func)
variable m.attr("var") = value
class py::class_<T>(m, "T")
nested namespace sub.def_submodule("name")📦 If you want automatic namespace discovery
You can use:
✔ pybind11 + Binder (LLVM-based autowrapper)
https://github.com/RosettaCommons/binder
Binder parses your C++ AST using Clang and generates pybind11 code, including:
    • namespaces
    • classes
    • functions
    • enums
Example:
binder --root-module mylib --prefix binder_output.cpp headers.hpp

Now you get full namespace reflection without writing manual glue code.🎯 Summary
To make pybind11 recognize namespaces:
    • Create submodules using def_submodule()
    • Put bindings into those submodules
    • Repeat for nested namespaces
If you want automation, use Binder or Clang-based tooling; pybind11 alone won't do it.If you want, I can generate a pybind11 namespace wrapper template for your FLTK project.