CGA-Example 1.1

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CGA-example version 1.1
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Overview :: 

 This is an example of a low-level binding to a c++ GUI library
and a mid-level CGA abstraction over it.  This was created primarily to 
spark
discussion in the [email protected] mailing list and secondarily to provide a
simple example that can be compiled using ghc without any language 
extensions. 

 I encourage those who code, to implement their ideas for the Common GUI API
using this simple framework.  This would allow all reviewers to understand
exactly what you are talking about by running your examples. 

 Fltk was chosen for its simplicity and portability.  I didn't use an 
existing
library because I wanted a short example where the source code is easy to
comprehend at all levels. 

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Changes :: 

v1.1 -- Using Heiarchy extention for module naming.  Completed CGA version 
of
 Box, Button, Window, and Widget.  Now using the agreed callback format.
 Initial child handeling support.  Using class-per-function naming.  Using
 MVar's in example CGA application for simplicity. 

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Questions :: 

1) How does the interface look in Test_midlevel.hs?  Is there any critiques 
in
 regard to using this style in CGA (Common GUI API)? 

2) Haskell has one namespace, the global one.  Since there would be a lot of
 function names and attributes in CGA, their names should be well thought 
out.
 Is there any ideas on how to handle this? 

3) How should children be handled?  I used both an attribute and a seperate
 function in this implementation. 

4) What do you think is important to have in the next version of 
CGA-example? 

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Running :: 

To run the examples, one needs a standard Haskell compiler with ffi (ghc) 
and
fltk installed (http://www.fltk.org).  run make.  If necessary, change the
makefile to modify for your configuration. 

Fl-stubs/* -- These are the stubs that are used to bind the c++ library to
 c functions.  This is required because the Haskell ffi standard does not
 specify any conventions for C++. 

Fl.hs
Fl/* -- These contain the bindings to the stub files.  They also provide
 a low-level interface for the fltk GUI toolkit. 

Test_lowlevel.hs -- This is a simple program demonstrating use of the 
low-level
 binding. 

Attributes.hs -- This code was taken from the htoolkit cvs server.  Simple
 modifications were made to suit our purposes. 

CGA.hs
CGA/* -- This is the Midlevel, CGA code wrapping the low-level Fl interface. 

CGA/CommonAttributes.hs
CGA/CommonMembers.hs
CGA/CommonSignals.hs  -- these are the support files for the
 one-class-per-function style as proposed on [email protected]. 

Test_midlevel.hs -- This is the same simple program as Test_lowlevel.hs 
except
 it uses CGA instead of Fl. 

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Cheers, 

David J. Sankel