added user-data to the resource

README.md

@@ -147,7 +147,7 @@ In order to create a resource and to bind it to the given loop, just do the foll
 
     auto tcp = loop.resource<uvw::TcpHandle>();
 
-The line above will create and initialize a tcp handle, thus a shared pointer to that resource will be returned.<br/>
+The line above will create and initialize a tcp handle, then a shared pointer to that resource will be returned.<br/>
 Users should check if pointers have been correctly initialized: in case of errors, they won't be.<br/>
 Another way to create a resource is:
 
@@ -156,6 +156,14 @@ Another way to create a resource is:
 
 Pretty annoying indeed. Using a loop is the recommended approach.
 
+The resources also accept arbitrary user-data that won't be touched in any case.<br/>
+Users can set and get them through the `data` member function as it follows:
+
+    resource->data(std::make_shared<int>(42));
+    auto data = std::static_pointer_cast<int>(resource->data());
+
+`uvw` expects a `std::shared_pointer<void>` and returns it, thus any kind of data is welcome.
+
 Remember from the previous section that a handle will keep itself alive until one invokes the `close` member method on it.<br/>
 To know what are the handles that are still alive and bound to a given loop, just do the following:
 

src/uvw/resource.hpp

@@ -85,7 +85,24 @@ public:
      */
     Loop& loop() const noexcept { return *pLoop; }
 
+    /**
+     * @brief Gets user-defined data. `uvw` won't use this field in any case.
+     * @return User-defined data if any, an invalid pointer otherwise.
+     */
+    std::shared_ptr<void> data() const {
+        return userData;
+    }
+
+    /**
+     * @brief Sets arbitrary data. `uvw` won't use this field in any case.
+     * @param uData User-defined arbitrary data.
+     */
+    void data(std::shared_ptr<void> uData) {
+        userData = std::move(uData);
+    }
+
 private:
+    std::shared_ptr<void> userData{nullptr};
     std::shared_ptr<void> ptr{nullptr};
     std::shared_ptr<Loop> pLoop;
     U resource;

test/uvw/resource.cpp

@@ -1,3 +1,4 @@
+#include <memory>
 #include <type_traits>
 #include <gtest/gtest.h>
 #include <uvw.hpp>
@@ -14,7 +15,12 @@ TEST(Resource, Basics) {
     ASSERT_FALSE(std::is_move_assignable<uvw::AsyncHandle>::value);
 
     auto loop = uvw::Loop::getDefault();
-    auto handle = loop->resource<uvw::AsyncHandle>();
+    auto resource = loop->resource<uvw::AsyncHandle>();
 
-    ASSERT_NO_THROW(handle->loop());
+    ASSERT_NO_THROW(resource->loop());
+
+    auto data = std::make_shared<int>(42);
+
+    ASSERT_NO_THROW(resource->data(data));
+    ASSERT_EQ(*std::static_pointer_cast<int>(resource->data()), 42);
 }