1. wxErlang
Mats-Ola Persson

2. wxErlang GUI library for Erlang write GUI applications cross platform
cross platform look and feel

3. Example A “stupid” tic-tac-toe application
No intelligent behavior is implemented
Just the (good) looks

4. Creating a window create_window() ->
wx:start(), % initialize wxErlang
% create a frame (window) with no parent
Frame = wx:frame(?NULL, ?wxID_ANY, “Hello World!”),
wx:show(Frame). % make the frame visible

5. Creating a window
Not very exciting: an empty window

6. Event-driven programming
Things “react” to mouse clicks, mouse movements, etc.
Event-handlers, callback functions

7. Events create_window() -> wx:start(),
Frame = wx:frame(?NULL, ?wxID_ANY, “Hello World!”),
% event-handler that reacts to close clicks
wx:connect(Frame, ?wxEVT_CLOSE_WINDOW,
fun(_,_) -> wx:quit() end),
wx:show(Frame).

8. Layouts Platform independent layouts Sizers
No fixed sized widgets, etc.
Arbitrary complex layouts
Let’s add the buttons!

9. Sizers
create_grid(Frame) -> Grid = wx:grid_sizer(3), % a grid sizer with 3 cols create_buttons(Grid, Frame, 9), % create 9 buttons Grid.
create_buttons(_, _, 0) -> ok;create_buttons(Grid, Frame, N) -> Button = wx:button(Frame, N), %a button without label
wx:add(Grid, Button), % add button to the sizer create_buttons(Grid, Frame, N - 1).

10. The result
A “shell” of a tic-tac-toe application

11. wxEtop Port of the old “etop” New features context menues
view running code
...

12. From the programmers point of view
wxErlang is verbose - like most GUI libraries
Trial-and-error - like most GUI libraries
Interface designers
XRCed, DialogBlocks, etc.

13. Design decisions Binding to the C++ GUI library wxWidgets
Get a lot for free
“free” features from wxWidgets
reduced maintenance work
wxErlang interface resembles wxWidgets C++ interface
free documentation(!)
Varför wxWidgets?

14. Translation scheme Easy Functions Multiple return values => tuples
...
Constants

15. Translation scheme Not as easy Classes
Overloading and overriding functions
Type system

16. Safety
Checks arguments
Types
Primitive values
Objects
Sanity

17. Implementational details
Most of the code is generated from wxWidgets headers
Implemented as a “port program”
Has a lot of bugs

18. Wrap up Current status - a prototyp wxEtop Perhaps 10% implemented
Future

19. Questions?