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// Copyright 2014 Renato Tegon Forti, Antony Polukhin.
// Copyright Antony Polukhin, 2015-2025.
//
// Distributed under the Boost Software License, Version 1.0.
// (See accompanying file LICENSE_1_0.txt
// or copy at http://www.boost.org/LICENSE_1_0.txt)
//[plugcpp_my_plugin_refcounting_api
#include "../tutorial_common/my_plugin_api.hpp"
#include <boost/dll/config.hpp>
class my_refcounting_api: public my_plugin_api {
public:
// Returns path to shared object that holds a plugin.
// Must be instantiated in plugin.
virtual boost::dll::fs::path location() const = 0;
};
//]
//[plugcpp_library_holding_deleter_api_bind
#include <memory>
#include <boost/dll/shared_library.hpp>
struct library_holding_deleter {
std::shared_ptr<boost::dll::shared_library> lib_;
void operator()(my_refcounting_api* p) const {
delete p;
}
};
inline std::shared_ptr<my_refcounting_api> bind(my_refcounting_api* plugin) {
// getting location of the shared library that holds the plugin
boost::dll::fs::path location = plugin->location();
// `make_shared` is an efficient way to create a shared pointer
auto lib = std::make_shared<boost::dll::shared_library>(location);
library_holding_deleter deleter;
deleter.lib_ = lib;
return std::shared_ptr<my_refcounting_api>(
plugin, deleter
);
}
//]
//[plugcpp_get_plugin_refcounting
#include <boost/dll/import.hpp>
inline std::shared_ptr<my_refcounting_api> get_plugin(
boost::dll::fs::path path, const char* func_name)
{
using func_t = my_refcounting_api*();
auto creator = boost::dll::import_alias<func_t>(
path,
func_name,
boost::dll::load_mode::append_decorations // will be ignored for executable
);
// `plugin` does not hold a reference to shared library. If `creator` will go out of scope,
// then `plugin` can not be used.
my_refcounting_api* plugin = creator();
// Returned variable holds a reference to
// shared_library and it is safe to use it.
return bind( plugin );
// `creator` goes out of scope here and will be destroyed.
}
//]
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