FLTK Event Handling

In FLTK when you create a widget you may assign a callback function to it. This event handler cannot be a non static class member. From what I read and understood there are three ways you can handle the events:
1- Let a static member do the job.
2- Let a static member call a non static member which does the job.
3- Create one static method which uses the user-data passed to it (callback second argument) as is called back to recognize which widget is the event source so it can call other methods to do the job respectively.

A combination of above methods can be used of course which make the matter more complex. I can write one static member to handle all button events and another one to handle window events.

Which method is better? What FLTK creators had in mind? FLTK documentation doesn't care to explain the matter. Is it really nice to create one static and one inline method for each event handler? is there an article to explain the matter?

Quote:

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Originally Posted by siavoshkc

This event handler cannot be a non static class member.

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GTK+ is the same way, in a C++ program. My personal preference would be to use a (private) static member that does the work directly. It involves less complexity (only one function call required), and it's a bit clearer as well. Someday, someone will create a GUI toolkit that uses modern C++ features like std::function and lambda functions for its event handlers. Until then, you just have to make do with what you have. Qt uses a slightly different mechanism, that produces automatically generated code, that hooks up events (signals) and handlers (slots) by name, catches the events, and calls the handlers directly.

So I also use one static private function. Now the question is how to choose a specific differentiator value for each handler. For example we can give a button integer 1 and another 2 two. Then in the static member switch by that number. I look for a maintainable and preferably automatic way to do so.

I'd have a separate static member function for each control. Especially if the controls do relatively distinct things.

I want to have one static member for all callbacks.

Quote:

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Originally Posted by siavoshkc

I want to have one static member for all callbacks.

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For what reason? How does it make the code clearer and easier to maintain?

This static member should call non static members to handle the callback. In the mean time I have a pair of one static and one non static function for each handler (As been told by FLTK manual) which is messy.

Made only one static member which receives "this" and do the job by itself. Thanks.