A fourth approach would be the proto package. It provides a thin
layer over environments making use of the prototype (aka object-based)
style of programming which is fundamental different relative to
class-based programming (although it is powerful enough to encompass
class based programming). The gsubfn package uses proto objects
as generalizations of replacement strings that hold state from one replacement
to the next. An application that may be closer to yours that uses proto
is ggplot2 which is a recent grid-based plotting package. The home page is at
http://r-proto.googlecode.com .
See the paper on prototype programming linked on the home page as well
as the package vignette.
On 9/14/07, Gerlanc, Daniel <Daniel.Gerlanc at geodecapital.com>
wrote:> Hello,
>
> I'm developing a GUI in R that will be used to monitor financial
> portfolio performance. The GUI will be distributed as an R package. So
> far, I've decided to use the "cairoDevice",
"RGtk2", "gWidgets", and
> "gWidgetsRGtk2" packages to develop the GUI. I am trying to
decide what
> would be the best way to structure the GUI would be.
>
> I've considered 3 approaches to building the GUI. The first would be
to
> use S4 classes. I would create parent "gui" object that would
store
> widgets or containers in slots. Other more specialized guis for
> different purposes would extend this parent "gui" object. The
> difficulty in this approach is R's use of pass-by-value. Once the gui
> object has been created, changing any of the slots of the gui requires
> returning a new GUI object or saving one off in a higher level
> environment and editing the slots directly. Editing the slots directly
> would completely bypass the S4 method dispatch.
>
> Another approach would be more functional. I would create variables
> that are global within the package or in their own environment and
> define the package function closures within this environment. This
> could work, but the code could get noisy when calls to have be made to
> distinguish between local variable assignment within the environment of
> the functions and assignment within the namespace of the package.
>
> The third approach I've been considering is using the R.oo package. I
> have never used this package before but it appears to provide similar OO
> features to Java. Because it allows references, it would seem to
> provide the features I'm looking for from both the S4 and functional
> approaches.
>
> Any comments or suggestions on these different approaches would be
> appreciated.
>
> Thank you.
>
> Sincerely,
>
> Daniel Gerlanc
>
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