Teach Yourself Borland C++ in 14 Days - portal

134 Day 5
That looks just a little intimidating, doesn’t it? The fact is, I even had to get some help from
my friends on the BCPPLIB forum of CompuServe (thanks, Paul!). Now look at the
equivalent using Borland’s Object Windows Library, shown in Listing 5.2.
Listing 5.2. OWL code to load and display a bitmap.
1: TDib dib(“test.bmp”);
2: TPalette pal(dib);
3: TBitmap bitmap(dib, &pal);
4: TClientDC dc(*this);
5: dc.SelectObject(pal);
6: dc.RealizePalette();
7: TMemoryDC memdc(dc);
8: memdc.SelectObject(bitmap);
9: dc.BitBlt(0, 0, bitmap.Width(), bitmap.Height(), memdc, 0, 0);
So which would you rather use? You don’t even have to know what these code snippets do
to make that decision. It’s easy to see that the OWL version is shorter and more readable.
(VCL makes the task even easier by providing a bitmap component that you drop on a form.
I don’t want to get ahead of myself, though, so I’ll save that discussion for a little later.)
These examples sum up what frameworks are all about. Frameworks hide details from you
that you don’t need to know about. Everything that is contained in Listing 5.1 is performed
behind the scenes in the OWL code in Listing 5.2. You don’t need to know every detail about
what goes on behind the scenes when OWL does its thing, and you probably don’t want to
know. All you want to do is take the objects that make up a framework and put them to use
in your programs.
A good framework takes full advantage of OOP. Some do that better than others. Borland’s
Object Windows Library and Visual Component Model are tremendous examples of objectoriented
programming. They provide the proper abstraction needed for you to rise above the
clutter and get down to the serious business of programming.
So What’s the Catch?
A little skeptical, are you? Good. You’re bright enough to figure out that if you have all of
that ease of use, you must be giving something up. Truth is, you are right. You might think
that a program written with a framework will be larger and slower than its counterpart written
in C. That’s partially correct. Applications written with frameworks don’t necessarily have
to be slower than programs written in C, though. There is some additional overhead inherent
in the C++ language, certainly, but for the most part it is not noticeable in a typical Windows
program.