Debugging Tip

Check if pappsoms_qmltyperegistrations.cpp includes your header:

#include "pappsomspp/processing/combiners/mzintegrationparams.h"

If not, that's the problem.

Indeed, it has the following include statement:

#if __has_include(<mzintegrationparams.h>)
#  include <mzintegrationparams.h>
#endif


ChatGPT said:

Ah, that’s the crux of the problem.

The line:

#if __has_include(<mzintegrationparams.h>)
#  include <mzintegrationparams.h>
#endif

in the auto-generated pappsoms_qmltyperegistrations.cpp only includes the header if it can be found as <mzintegrationparams.h> in the global include paths — i.e., not using a relative or subdirectory-prefixed path like pappsomspp/processing/combiners/mzintegrationparams.h.
🔍 Why it fails

In your setup, the header is probably only available as:

#include "pappsomspp/processing/combiners/mzintegrationparams.h"

and not as:

#include <mzintegrationparams.h>

So __has_include(<mzintegrationparams.h>) returns false, and your class is never included into the generated file — meaning pappso::MzIntegrationParams is undefined.
✅ Solution Options
✅ Option 1: Add an #include path

Make sure the directory containing mzintegrationparams.h is added to your public include directories:

target_include_directories(PappsoMS PUBLIC
    ${CMAKE_CURRENT_SOURCE_DIR}/pappsomspp/processing/combiners
)

Then #include <mzintegrationparams.h> will resolve correctly during auto-generation.

✅ Option 2: Rename header or create a forwarding header

Create a file at pappsomspp/processing/combiners/mzintegrationparams.h that’s publicly visible and easy to include. Or, even better, put a symlink or forwarding header in a top-level include directory:

// in include/mzintegrationparams.h
#include "pappsomspp/processing/combiners/mzintegrationparams.h"

Then ensure include/ is in your public include directories.
🧹 Also Recommended

Run a clean rebuild after modifying include paths or QML module definitions. Qt code generation can cache outdated assumptions.
✅ Summary Fix Plan

To fix your issue:

    Add this to your CMake target:

    target_include_directories(PappsoMS PUBLIC
        ${CMAKE_CURRENT_SOURCE_DIR}/pappsomspp/processing/combiners
    )

    (Optional but safer) Change your header guard or filename to match <mzintegrationparams.h> (or create a forwarding header).

    Run rm -rf build-area && cmake ... && make.

Let me know if you'd like help creating a forwarding header or adjusting the CMake include paths!
You said:
This is bad design ! when including internal header files in a given projet  the bracket notation is discouraged, no ?
ChatGPT said:

You're absolutely right — using #include <...> for internal project headers is not good design. That notation is traditionally reserved for external, system, or library headers. For internal headers, the recommended practice is:

#include "relative/path/to/header.h"

💡 So why is Qt doing this?

Qt’s qt_add_qml_module() generates code that uses:

#if __has_include(<mzintegrationparams.h>)
#  include <mzintegrationparams.h>
#endif

This is a generic mechanism to auto-include any QML-annotated class headers by filename only, assuming the header is available in the compiler's include path — even if it's not great from a software architecture point of view.

So yes, this is a design compromise Qt makes to support auto-registration of QML types. The underlying logic is:

    Qt scans for QML-exported C++ types via QML_ELEMENT, etc.

    It generates registration code and tries to include the header by guessing the filename.

    To avoid hardcoding paths, it uses __has_include(<name.h>) and assumes the project has exposed the header in the public include path.

✅ Correct Design Approach for You

You can preserve good internal design and still make this work without polluting your project with bad #include <...> style.
✅ Recommended Fix with Correct Design

    Keep your internal includes clean:

        Keep using "pappsomspp/processing/combiners/mzintegrationparams.h" in your own code.

        Do not switch to <mzintegrationparams.h> in your project.

    Work around Qt’s generator expectations:

        Add a forwarding header for the specific classes you export to QML, and place it in an internal "qml_export" directory:

include/pappsoqml/mzintegrationparams.h

with contents:

#pragma once
#include "pappsomspp/processing/combiners/mzintegrationparams.h"

Add this directory to your include paths for the Qt-generated code:

        target_include_directories(PappsoMS PUBLIC
            ${CMAKE_CURRENT_SOURCE_DIR}/include/pappsoqml
        )

        This satisfies the generator's <mzintegrationparams.h> lookup without polluting your internal logic or exposing deeply nested paths.

    (Optional but clean) Use CMake's PUBLIC_HEADERS if available to declare headers that should be "publicly visible", and map those into a clean public include structure.

🧵 TL;DR

Yes, Qt’s generated #include <...> for internal headers is poor design — but you can work around it cleanly by:

    Keeping your internal includes with "...".

    Providing Qt a shim/forward header in a separate include directory just for QML exports.

    Avoiding the need to expose all your internal directories via target_include_directories.

Let me know if you'd like a snippet showing exactly how to structure the forwarding headers!
You said:
Waouw, very good that worked !
ChatGPT said:

That's fantastic to hear — well done! 🎉

By keeping your internal headers clean and using a dedicated forwarding header just for Qt's generator, you've got the best of both worlds:

✅ Clean project architecture
✅ Working QML integration
✅ No need to misuse angle brackets for internal includes

If you end up registering more classes to QML, you can keep dropping lightweight forwarding headers in your include/pappsoqml/ folder — it's a small maintenance cost for a very clean separation.

If you need help automating that or managing module versioning, I'm here. Happy coding! 🚀
