Re: What is GNOME office?

["Dom Lachowicz" <cinamod hotmail com>]

Miguel wrote:
> Even if you use those libraries, that does not mean that programmers
> write code against those libraries.  Programmers have to write code
> against your XP code base, or am I wrong?
This is a much more sensible question.

A lot of our code lies _solely_ in an XP layer. This applies to our 
piece-table code, formatting code, import/export code, and some other bits 
(we do conditionally use libxml2 in our generic XML import class though).

Then we have a layer that is a mix between X-Platform and Platform-specific 
code. The XP code is extended by platform-specific code. The 
platform-specific code handles the actual display of dialogs, widgets, 
signals/callbacks, and the like. Its callbacks marshall the interesting data 
obtained from the p-specific code back to the XP layer. The XP layer then 
handles the result accordingly. An example could be obtaining a filename 
from a file-selector control. The p-specific code would pop up a 
GtkFileSelector on unix and get a file's name. Then it would pass the 
filename back to XP code which would then do the equivalent of this:

if(fileExists(filename))
  abiwordApplication->openFile(filename);

The platform-specific code utilizes the gdk, gal, gtk, etc... libraries on 
Gnome for example. Somewhere in XP code, we say "I want a FileSelector, make 
me one." We then create the proper platform-specific dialog (which C++ 
extends its XP base-class). So our XP layer acts as an "insulator" to the 
p-specific code. In XP code, no one ever says "go make me a gal color 
combo." Instead the question is more generic - "go get me a color combo 
box." So yes, in XP code, programmers only make calls against the XP code 
base.

But in the plaform specific code (which there is a lot of), it's perfectly 
legal to say "get me a gal color combo" beacuse the gal color combo fulfills 
the requirement of a "color combo box."

Think of it as C++ wrapper like wxWindows or a GDK backend if you'd like - 
you say: w = gdk_window_new(); On X, that call creates a new X-Window. On 
Win32, a new HWND. Plus there's usually some work needed to get the X-Window 
or HWND to conform to the definition/spec of a GdkWindow. You don't really 
care how gdk_window_new() does its business, just that you get a GDK window 
to draw to. If what you get conforms to the GdkWindow spec, you're perfectly 
happy. This is what our C++ platform-specific does by subclassing our XP 
layer. By separating things into a base gdk library, GTK is much more 
portable and easy to port. The same applies to Abi. Try to think of how Abi 
does its business as something like that.

So no, not all programmers write code against the XP code base. In certain 
portions of our source tree, this *is* true. In other portions, we write 
p-specific code to implement our base-class' spec.

Thanks,
Dom


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