Code Generation for Boilerplate#

The process of sharing objects between engines involves two fundamental steps: defining the data structure and establishing the protocol to represent the data type as Objects. To alleviate the integration burden with custom data types, Vineyard offers an auto-generation mechanism.

This mechanism, known as VCDL, relies on the custom annotation [[shared]] applied to C++ classes.

Consider the following C++ class Array as an example:

template <typename T>
class [[vineyard]] Array {
    [[shared]] const T& operator[](size_t loc) const { return data()[loc]; }
    [[shared]] size_t size() const { return size_; }
    [[shared]] const T* data() const {
        return reinterpret_cast<const T*>(buffer_->data());

    [[shared]] size_t size_;
    [[shared]] std::shared_ptr<Blob> buffer_;
  • When applied to classes: the class itself is identified as a shared vineyard object, and a builder and resolver (see also Builders and resolvers) are automatically synthesized.

  • When applied to data members: the data member is treated as a metadata field or a sub-member.

  • When applied to method members: the method member is deemed cross-language sharable, and FFI wrappers are automatically synthesized.