The class Predictor (https://github.com/dmlc/xgboost/blob/master/include/xgboost/predictor.h) seems a very usable interface in the scenarios where model is trained in python/R and prediction function is used in c++.
But this interface seems non usable as the interface refers to gbm::GBTreeModel class for model definition which is not exposed for public usage.
We only expose interfaces/classes defined in include/ while gbm::GBTreeModel is defined under src/ (https://github.com/dmlc/xgboost/blob/master/src/gbm/gbtree_model.h)
Probably that’s why we don’t find any examples of usage of Predictor class, despite hitting the requirements.
If other agree, I can go ahead and create an issue for better tracking and fixing