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yves.yang@xxxxxxxxxxx wrote:
What's your definition of representation? I guess it is EMF object which
defines UI. With EMF, you have to deal this new layer. And of course, you
need to a "live model".
Both TM and XWT resources (files) are UI representations, based on EMF
and XAML/XML, respectively. The fact that XWT doesn't need it once it
has been loaded and the UI rendered doesn't change this fact. Tools that
are used for editing must have it in memory.
In XWT, this layer doesn't exist. XWT can be considered as a simple
Loader, which read XML file and create immediately SWT widget. So we don't
care of "live model" or precisely "live layer". It is always "live".
What I think you mean is that the XWT representation doesn't exist in
addition to the SWT object during runtime, once the latter has been
built. You throw it away, and the application programmer uses the SWT
objects for handling events and manipulating the UI. So it's SWT that is
"live", not XWT.
There are three kinds of advantages of a live representation (that I can
think of at this moment):
- It provides more flexibility, e.g. even if SWT doesn't support
changing style bits, XWT could allow it and under the covers
re-instantiate the SWT object
- It provides a higher abstract level or otherwise mentally cleaner or
simpler model, e.g. a simpler class hierarchy, uniform styling model,
etc. This is not that relevant for XWT, since it is SWT-oriented by design.
- The underlying representation (EMF or XML) may better support generic
operations like copying hierarchies, visiting nodes, querrying,
observing, persisting, transformations etc.
Hallvard
