How WPF gets GUI programming right

WPF is another in a long line of Microsoft UI related technologies, each promising more than the one before. WPF is basically Silverlight for the desktop (or, if you prefer, Silverlight is WPF for the web). We have been building an application in WPF as of late at my place of employment, and I’d thought I’d post what I thought that WPF does right.

The biggest thing is that WPF builds UIs declaratively. I cannot stress enough how important I think this really is. The biggest pain about using Java’s Swing framework was writing long sequences of code that initialized controls in a form’s constructor. Under the hood, Windows forms works pretty much the same way. The biggest difference is that Microsoft ships a nice designer with Visual Studio, so the raw kludginess of the approach is hidden from most programmers, since they look at everything through the lens of the designer.

The declarativeness goes beyond simply allowing one to declare that widgets will exist to their layout (via the Grid mechanisms–really, these should be used by default and the designer left on the shelf) and their data flow. The latter is particularly interesting. ASP.NET has data binding, but the version employed by WPF is far more sophisticated. When I jumped back to an ASP.NET project, I immediately found myself missing the power of WPF databinding, but to add it to a web framework would unquestionably require a continuation based framework like the one employed by Weblocks or Seaside.

The importance here is that both the interface and how it interacts with data can be declared. Many GUI designers and markup languages have come along that allowed one to declare the layout, but few, if any, mainstream GUI designers have allowed so much expressiveness.

The hard part about all this, is that C# is a statically typed language and, as a result, a lot of these features are based heavily on reflection which is a performance hit, due to the fact that the JIT compiler cannot really optimize these things. Perhaps it was just my imagination, but I feel pretty sure that WPF applications lag behind their windows forms cousins in terms of speed.

All in all, though, WPF is a fine framework, though.

Polymorphism, Multiple Inheritance, & Interfaces…Pick 2.

The title for this post comes from a statement that was brought up by a  coworker as having been said to him. The overall point of this post will be simple: given that choice, your answer should be obvious: you want polymorphism and multiple inheritance, because there is nothing that you can do with interfaces that you cannot do with multiple inheritance.

Interfaces provide two things, depending on their use: a form of multiple inheritance in languages that do not otherwise support it and design-by-contract capabilities. Clearly, in the former case, you are better off with multiple inheritance, as you receive the full power of the feature. In the latter case, it is trivial to create an almost-empty class that acts as an interface, if that is the effect you are after.

The main objection raised was the counter example: what if you have a class Animal and another class Plant. Surely you do not want a programmer to inherit from both? That would not make sense. To which I would answer Why not? If it makes sense to whomever wrote it, why prevent it? They might, after all, be creating something for the little shop of horrors.

Largely, I  think the thinking that interfaces are somehow superior to multiple inheritance comes from never having used multiple inheritance in a system built from the ground up to support it (like CLOS in Common Lisp) as multiple inheritance strictly supersedes interfaces.

The Literature

Looking back at my last few posts, something occurred to me: a lot of the more exotic focus of this blog has been lost. While I enjoy examining MVVM and QuickBooks, one of the whole points of this blog was to offer a fusion between useful code monkey concepts and computer scientist (hence, the domain name of this site). Lately, there has not been much “scientist” at the mad computer scientist.

One of my new series of posts is going to be literature reviews. I have a massive reading list of computer science papers queued up as well as some other materials. In these posts, I will read a journal article or watch a lecture and post my notes and thoughts about it. The first one will be coming soon, so look out for it.

More on Microblogging and Programming

I had been rolling around some thoughts on microblogging and programming since my last blog post. First of all, I found it interesting that Twitter started life as an internal project before getting VC funding. This reenforces, to me, the value of what I as saying, which is that microblogging for more limited audiences and topics is more useful than the present day and age where we have people microblogging about brushing their teeth.

I have also been interested in doing more work on Sheepshead. According to gitorious, my last commit was over a month ago. Such are the results of having a family, a job, and a life–but I really want to get back to working on it. As I start gearing it all up again, I have decided to try a little experiment. Instead of simply waiting on someone else to try out microblogging for a small development team, I am going to try to bootstrap a small team while microblogging. As I develop Sheepshead and push it forward, I am going to try and use microblogging to mull over design decisions and announce progress.

The service I have decided to use for this endeavor is Identi.ca (you can see the stream here), rather than the more ubiquitous Twitter. I did this for a few reasons, chief among them being that I expect there to be more engineering types as well as more open source-minded individuals on Identi.ca. Another important consideration is that Identi.ca allows its users to export data. My intention is to keep backups of the information on the feed, so that if something were to happen to Identi.ca and the project attained a meaningful size, a StatusNet instance could be setup, even if only as a stopgap.

We will see how this all goes (or if it does–I can definitely see how Sheepshead is sort of a niche development). In the mean time, I am going to try and get some code written.