Is Delphi Dead? No.

A few months ago Alex Miller pointed me to this Delphi doom article (the site appears to be down at the moment), which reminded me to post about the same topic. Here goes.

Delphi shipped in 1995, and its demise has been declared frequently since 1997 or so. In a sense this demise is true, yet also false. Delphi’s current popularity is very different in form (not only in magnitude) from that of Java, C#, etc. Delphi is used substantially by commercial software vendors, and only rarely by enterprises. An ugly reality of the software industry is that the bulk of software developers nationwide work inside large non-software companies, so this usage pattern most likely does not produce the level of unit sales that Codegear (Borland’s dev-tools subsidiary) would like to see. It does, however, produce an enormous number of Delphi application instances running “in the field”, used by real paying end users, who don’t care (or know) what development tools were used to build the software they buy. Many commercial software products, both those in shrinkwrap at retail stores and those for vertical markets, are written in Delphi and will continue to be, because there are very few other good choices for high quality (polished) native Win32 GUI software. In these markets, shipping a Java or .NET app can be a competitive disadvantage (though to a lesser extent over time), and old-style VB is a sad joke.

I don’t think Delphi is eligible for demise until the dominant desktop operating system ships with a dominant runtime platform “in the box”. For example, if all of this happens at the same time:

  • Microsoft ships Windows with the .NET runtime already installed
  • That version Windows is the commonly deployed version
  • That version of the .NET runtime is the commonly targeted version

At that time, the .NET platform (with the language of your choice) could be a compelling replacement for Delphi in its niche. There is a lot to like about .NET (and Java, and I use them both), but I’m not holding my breath for the above conjunction.

Over at Oasis Digital we have several ongoing Delphi projects in which we develop and extend in-house, enterprise applications. These projects feel notably lonely (very few developers here in the midwest use Delphi), and the Delphi language leaves a lot to be desired (such as garbage collection) – but the resulting software works very well for our customers, especially when we add in a bit of Lua or Prolog (story coming someday…).

Delphi is not dead. It’s not at the top of the popularity charts, and won’t be. It probably shouldn’t be your first choice for a new in-house enterprise application starting today, because of the network effects of Java and .NET popularity. But Delphi is not going away anytime soon, and is a great choice for certain classes of projects.

Optimize Hierarchy Queries with a Transitive Closure Table

Last year I posted about the use of a Joe Celko-style nested set hierarchy representation, for fast hierarchy queries. Here I will describe another approach which is simpler to query, but more wasteful of space. I did not invent this transitive closure approach, I learned of it from several directions:

There are two (main) places to put the code for building a closure tables: in your application code, or in your database. The application approach is nice if you are aiming to avoid vendor-specific SQL code, but it is quite simple in SQL, and therefore not a big problem to recode for another RDBMS if the need arises. The SQL approach also avoids round-tripping the relevant data in and out of the database. Therefore, the approach I generally recommend for this is an SQL stored procedure / function.

Here is a simplified PostgreSQL stored procedure to do the job; note that his assumes a “widget” table with a widget_id and parent_id (the “adjacency” representation of a hierarchy), and a widget_closure table with fields (ancestor_id, widget_id, depth):

CREATE OR REPLACE FUNCTION populate_widget_closure()
RETURNS integer AS '
  distance int;
  delete from widget_closure;
  insert into widget_closure
    select widget_id, widget_id, 0 from widget;

  FOR distance in 1..20 LOOP
    insert into widget_closure
    select uc.parent_id, u.widget_id, distance
      from widget_closure uc, widget u
      where uc.child_id=u.reports_to_id
        and uc.distance = distance-1;
' LANGUAGE plpgsql;

This sample code assumes a maximum depth of 20, and has no error checking. It will blindly miss greater depths and produce garbage if there is a “loop” in the ancestry. I recommend both arbitrary depth handling and error checking for production use.

Once your transitive closure table is populated, querying it is extremely fast and simple. You can get all the descendants of widget 12345 with the query “select widget_id from widget_closure where ancestor_id=12345”. Of course, this hierarchy representation, while simple to generate, is not simple to incrementally update as the hierarchy changes. The most straightforward way to use it is as a cache, regenerated as needed.

Shoes, a new Ruby GUI toolkit

Last year I gave a talk on Ruby GUI toolkits, and concluded that none of those I looked at were compellingly slick or mature. There is a new player on the field now (thus certainly not mature, but interesting nonetheless): Shoes, from why the lucky stiff.

Shoes creates native applications with a Web feel. It is not built atop GTK, Qt, etc., but rather directly on the relevant native API (Win32 on Windows, for example). Shoes has a lot of potential, which it can realize only if a community accrues around it, leading to lots of polish and a rich widget set.

One thing that surprised me about the Shoes install it that, as far as I can tell, it includes its own Ruby install; I installed Shoes on a machine with no (obvious) Ruby installation and it worked.