The Callbacks should have a "void*" data in order to pass the "this" pointer in a class usage

[fabri9532]

Let me explain: When I use the library in a class, I need to declare tha Callback procedure as "static" member. With a static Callback procedure, I need to known from wich class object the call is made. So I need the "this" pointer to be passed to the Callback.

Modification example: Set Total callback: setTotalCallback( const TotalCallback &callback, void lpData ) TotalCallback: void(uint64_t total_size, void lpData)

[rikyoz]

I think that this situation can be solved without requiring the modification of the callbacks signatures. In fact, in this case there are two options for the callback function:

• Use a lambda which captures the this pointer.

  compressor.setTotalCallback( [this]( uint64_t total_size ) {
      //both this and total_size are accessible
  });

• Use std::bind with a (non-static) member function which takes the same parameters of the callback you need.

  void MyClass::method() {
      //...
      auto callback = std::bind( &MyClass::callbackMethod, this, std::placeholders::_1 );
      compressor.setTotalCallback( callback );
      //...
  }
  //...
  void MyClass:callbackMethod( uint64_t total_size ) {
      //callback
  }

[fabri9532]

Many thanks for the reply. The solution you proposed fully meets my needs.

Fabrizio.

[rikyoz]

You are welcome, glad to help!

Riccardo