Add back instantiateGrad arg in Scheduler::backward().

include/aidge/scheduler/SequentialScheduler.hpp

@@ -54,7 +54,7 @@ public:
     /**
      * @brief Run the provided Computational Graph with a batch of data
      */
-    void backward();
+    void backward(bool instantiateGrad = true);
 
 private:
     SchedulingPolicy mSchedulingPolicy;

python_binding/scheduler/pybind_Scheduler.cpp

@@ -34,7 +34,7 @@ void init_Scheduler(py::module& m){
     py::class_<SequentialScheduler, std::shared_ptr<SequentialScheduler>, Scheduler>(m, "SequentialScheduler")
     .def(py::init<std::shared_ptr<GraphView>&>(), py::arg("graph_view"))
     .def("forward", &SequentialScheduler::forward, py::arg("forward_dims")=true, py::arg("data")=std::vector<Tensor>())
-    .def("backward", &SequentialScheduler::backward)
+    .def("backward", &SequentialScheduler::backward, py::arg("instanciate_grad")=true)
     ;
 
     py::class_<ParallelScheduler, std::shared_ptr<ParallelScheduler>, Scheduler>(m, "ParallelScheduler")

src/scheduler/SequentialScheduler.cpp

@@ -73,7 +73,12 @@ void Aidge::SequentialScheduler::forward(bool forwardDims, const std::vector<std
     }
 }
 
-void Aidge::SequentialScheduler::backward() {
+void Aidge::SequentialScheduler::backward(bool instanciateGrad) {
+    // create ad set Grad values
+    if (instanciateGrad) { compile_gradient(mGraphView); }
+
+    // TODO: Check output grad are not empty
+
     // Generate scheduling *only if empty*
     // If scheduling was already generated (in one or several steps, i.e. one or
     // several successive call to generateScheduling()), do not generate it twice