Avendish data / message object template

A canonical template for making data / message objects with Avendish: a single C++ object that processes strings (and other non-audio data) and is compiled, without rewrite, to the host formats that have a real object model.

It is the message-processing counterpart of the audio, video and geometry templates.

What gets built

The avnd_make_object(...) macro in CMakeLists.txt instantiates the object back-ends — deliberately not the audio plug-in formats (VST3 / CLAP / …):

Back-end	Object kind	SDK required
Max/MSP	a Max external	Max SDK
Pure Data	a Pd external	PureData headers (m_pd.h)
TouchDesigner	a CHOP (message)	TouchDesigner Custom Operator SDK
Godot	a GDExtension node	none — godot-cpp is fetched automatically
Python	an importable extension module	pybind11 + Python dev headers
ossia score	a process	libossia

Back-ends whose SDK is not provided are silently skipped.

The object

src/Model.hpp implements MyDataProcessor: it takes a string input, applies a case/reverse Operation, and emits the transformed string on its output. It also exposes a set_prefix message (a halp_mem_fun) that prepends a prefix to every output — showing string ports (halp::val_port<…, std::string>), an enum control (halp::enum_t), input-driven recompute (update()), and message handlers.

Start from there: change the ports/messages and rewrite operator(). See examples/Complete/CompleteMessageExample.hpp in Avendish for the full set of string / message / callback features.

Building

cmake -S . -B build -G Ninja -DCMAKE_BUILD_TYPE=Release
cmake --build build

With no extra options this builds the Godot back-end (it fetches godot-cpp automatically). Pass the relevant SDK paths to enable the others — see the Github actions workflow, which builds the project on clean VMs via the shared ossia/actions/avendish-template action:

• Max/MSP: -DAVND_MAXSDK_PATH=path/to/max-sdk-base
• Pure Data: make m_pd.h findable, e.g. -DCMAKE_INCLUDE_PATH=path/to/pure-data/src
• TouchDesigner: -DTOUCHDESIGNER_SDK_PATH=path/to/CustomOperatorSamples
• Python: -Dpybind11_DIR="$(python -m pybind11 --cmakedir)"
• ossia score: install libossia