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Project Notes - gnavi_inside
GNAVI Projects Notes

GNAVI - The GNU Ada Visual Interface 
	The Total Open Source Answer to Delphi and the Visual Basic

The GNAVI project contains:

GNAT - the GNU Ada compiler

GWindows  - Native GUI framework for Win32 (OS X and Gtk in the
            works, possible other targets A# Windows.Forms for .NET)
	    Bindings to databases via Active Data Objects (ADO which
	    gives access to ADO, OLEDB, JetDirect and ODBC) and MySQL

GNATCOM   - Active X controls on Win32, Plug-Ins on OS X (OS X plug-ins
            actually use MS's COM specs)

GNAVI IDE - The RAD IDE Environment for GNAVI

The word "GNAVI" is intentionally overloaded (as is Delphi) to mean:

The programming Environment as a whole and all its parts including the
frameworks The GUI Builder / IDE Even the "programming language".

No body talks about programming in Object Pascal in the Delphi
IDE. They program in Delphi. This is an important factor for the
success of such a project. To the wise it means "Ada" inside to others
it means cool up and coming open source VB / Delphi, runs on Windows,
OS X and Unix and is something that I can get a job with, ie. "it's
just like Delphi and VB but cooler, open source and has ultra cool
built in features like tasking, distributed computing and is built for
'serious' projects not just IT department toys". The "Programming in
GNAVI" marketing campaign is being put together now. It will target
Delphi and VB users to switch to Open Source. When the GTK port is
done it will include general push on the Linux community as a whole to
rally behind THE Open Source Delphi/Kylix/VB replacement.

The GNAVI RAD IDE environment is a combination of three "ideas":

1. The "GUI Builder"
2. The Editor / IDE.
3. The "Interactive Code Generator" (ICG)

A working ICG is available and snap shots of the GUI Builder and IDE
are being made regularly available. GPS / Emacs can be used until the
IDE is complete for text editting.

The GUI Builder development has already started with work on a series
of "Wizards" to generate windows with controls bound to datbases,
dialogs, etc.  The interactive layout of controls will be coming soon
as well there is already an early prototype designed a year ago that
can do some basic lay outs. The specs for "GNAVI Plug Ins" is being
developed now also.

The thee parts ideally should be tightly integrated, but for now it
will be possible to use external tools such as GPS or Emacs or other
editors with a little bit of discipline on the users part. In the
future an editor will be integrated and tighter support with GPS is

The magic of GNAVI is in the relationship between the three parts the
GUI Builder, the ICG and the Editor / the User. Everything is always live
with the ability to make changes on the GUI Builder and have those changes
reflected instantly in the editor and changes made in the code realized in
the app and where appropriate the GUI Builder.

The design as a whole is geared for ease of use, programming and
learning. The applications created with GNAVI are easily extended and
changed offer true native look and feel, and have available a good
selection of database, XML and Web controls already.

Internal relationships:

The GUI Builder emits XML that is parsed by the ICG when asked by the
GUI Builder (this message includes "renames" of windows, controls and
handlers). See XML sample: http://www.gnavi.org/gnavi/gnavi_xml.txt

The XML format from the GUI builder is a simple lay out of controls,
properties and names of handlers.

The GUI Builder will use a "database" of XML that describes available
windows and controls, their properties and the their handler

The ICG as it is implemented now uses a set of code templates and is
designed in a way that allows it to handle even user derivied windows
and controls.

Interactive Code Generation:

(See actual generated code at http://www.gnavi.org/gwindows/gnavi-code.zip)

1. When a user choose to create a new application in the GUI builder, it
will generate the following:

A. The application main procedure that "with"s each window in the
   project and starts the Mesage_Loop (in the example this is

B. The window spec and package. The new window type is extended from
   whatever window type is in the XML (in the example this is

C. A separate procedure (in our example
   my_window_package-on_create.adb) for doing the GUI layout that is
   regenerated every time.

D. A project file that references the other windows.

2. The lay out of the controls and assigning of handlers to the window
   and its controls is all in a separate (unit) procedure On_Create
   that is part of the OO extension of the Window_Type that is
   regenerated on the fly and not touched by the user (in the example
   this is my_window_package-On_Create.adb).

3. The extended Window_Type (or what ever Type they choose to extend
   from in the GUI builder) contains the control instance variables
   and additional data that can be entered in the code under the --
   GNAVI: comment by hand or perhaps also from the GUI.

4. If a handler is assigned in the GUI builder to a control or window
   and it does not exist in the code yet it is generated. If it
   already exists, it is left alone.

5. If a control is renamed, the window, the handler renamed in GUI
   builder (and in the future the code as well) renamed in code (or
   XML, ie. for the GUI builder in the future).

Notes about the generated code:

As you can see, GWindows and as such GNAVI was designed to allow for
coding in a fashion that is "simple" both in look and in use, but can
be extend easily in the midst of a GNAVI / Delphi like environment. It
minimizes as much as possible the aspect of Ada, but not completely as
to loose the advantages of or prevent the future use of it, being an
"engineering" tool. It opens up Ads as the bridge between coding and

(c) 1999-2004 All Rights Reserved David Botton