wxErlangMats-Ola Persson

wxErlang

•GUI library for Erlang

•write GUI applications

•cross platform

•cross platform look and feel

Example

• A “stupid” tic-tac-toe application

• No intelligent behavior is implemented

• Just the (good) looks

Creating a window

create_window() ->wx:start(), % initialize wxErlang

% create a frame (window) with no parentFrame = wx:frame(?NULL, ?wxID_ANY, “Hello World!”),

wx:show(Frame). % make the frame visible

Creating a window

• Not very exciting: an empty window

Event-driven programming

•Things “react” to mouse clicks, mouse movements, etc.

•Event-handlers, callback functions

Events

create_window() ->wx:start(),Frame = wx:frame(?NULL, ?wxID_ANY, “Hello World!”),

% event-handler that reacts to close clickswx:connect(Frame, ?wxEVT_CLOSE_WINDOW,

fun(_,_) -> wx:quit() end),

wx:show(Frame).

Layouts

•Platform independent layouts

•Sizers

•No fixed sized widgets, etc.

•Arbitrary complex layouts

•Let’s add the buttons!

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).

The result

• A “shell” of a tic-tac-toe application

wxEtop

• Port of the old “etop”

• New features

• context menues

• view running code

• ...

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.

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(!)

Translation scheme

•Easy

•Functions

•Multiple return values => tuples

•...

•Constants

Translation scheme

•Not as easy

•Classes

•Overloading and overriding functions

•Type system

Safety

•Checks arguments

•Types

•Primitive values

•Objects

•Sanity

Implementational details

•Most of the code is generated from wxWidgets headers

•Implemented as a “port program”

•Has a lot of bugs

Wrap up

•Current status - a prototyp

•wxEtop

•Perhaps 10% implemented

•Future

Questions?