Class resource_loader
Synopsis
#include <src/entt/resource/loader.hpp>
template<typename Loader, typename Resource>
class resource_loader
Description
Base class for resource loaders.
Resource loaders must inherit from this class and stay true to the CRTP idiom. Moreover, a resource loader must expose a public, const member function named load that accepts a variable number of arguments and returns a shared pointer to the resource just created.
As an example:
struct my_resource {};
struct my_loader: entt::resource_loader<my_loader, my_resource> {
std::shared_ptr<my_resource> load(int) const {
// use the integer value somehow
return std::make_shared<my_resource>();
}
};
In general, resource loaders should not have a state or retain data of any type. They should let the cache manage their resources instead.
- Note
- Base class and CRTP idiom aren't strictly required with the current implementation. One could argue that a cache can easily work with loaders of any type. However, future changes won't be breaking ones by forcing the use of a base class today and that's why the model is already in its place.
- Template Parameters
Loader- Type of the derived class.Resource- Type of resource for which to use the loader.
Mentioned in
- Resource Management / The resource, the loader and the cache
Source
Lines 44-59 in src/entt/resource/loader.hpp.
template<typename Loader, typename Resource>
class resource_loader {
/*! @brief Resource loaders are friends of their caches. */
friend struct resource_cache<Resource>;
/**
* @brief Loads the resource and returns it.
* @tparam Args Types of arguments for the loader.
* @param args Arguments for the loader.
* @return The resource just loaded or an empty pointer in case of errors.
*/
template<typename... Args>
[[nodiscard]] std::shared_ptr<Resource> get(Args &&... args) const {
return static_cast<const Loader *>(this)->load(std::forward<Args>(args)...);
}
};