OOPS Programming Languages
There are almost two dozen major object-oriented programming languages in use today. But leading commercial languages are fewer in number. This page covers just a few of the most popular. These are:
C++ is an object-oriented version of C. It is compatible with C (it is actually a superset), so that existing C code can be incorporated into C++ programs. C++ programs are fast and efficient, qualities which helped make C an extremely popular programming language. It sacrifices some flexibility in order to remain efficient, however. C++ uses compile-time binding, which means that the programmer must specify the specific class of an object, or at the very least, the most general class that an object can belong to. This makes for high run-time efficiency and small code size, but it trades off some of the power to reuse classes.
C++ has become so popular that most new C compilers are actually C/C++ compilers. However, to take full advantage of object-oriented programming, one must program (and think!) in C++, not C. This can often be a major problem for experienced C programmers. Many programmers think they are coding in C++, but instead are only using a small part of the language's object-oriented power.
Smalltalk is a pure object-oriented language. While C++ makes some practical compromises to ensure fast execution and small code size, Smalltalk makes none. It uses run-time binding, which means that nothing about the type of an object need be known before a Smalltalk program is run.
Smalltalk programs are considered by most to be significantly faster to develop than C++ programs. A rich class library that can be easily reused via inheritance is one reason for this. Another reason is Smalltalk's dynamic development environment. It is not explicitly compiled, like C++. This makes the development process more fluid, so that "what if" scenarios can be easily tried out, and classes definitions easily refined. But being purely object-oriented, programmers cannot simply put their toes in the o-o waters, as with C++. For this reason, Smalltalk generally takes longer to master than C++. But most of this time is actually spent learning object-oriented methodology and techniques, rather than details of a particular programming language. In fact, Smalltalk is syntactically very simple, much more so than either C or C++.
Unlike C++, which has become standardised, The Smalltalk language differs somewhat from one implementation to another. The most popular commercial "dialects" of Smalltalk are:
VisualWorks is arguably the most powerful of Smalltalk's. VisualWorks was developed by ParcPlace, which grew out of the original Xerox PARC project that invented the Smalltalk language. VisualWorks is platform-independent, so that an application written under one operating system, say, Microsoft Windows, can work without any modification on any of a wide range of platform supported by ParcPlace, from Sun Solaris to Macintosh. VisualWorks also features a GUI (Graphic User Interface) builder that is well-integrated into the product.
Smalltalk/V and Visual Smalltalk
Digitalk's versions of Smalltalk are somewhat smaller and simpler, and are specifically tailored to IBM compatible PCs. A Macintosh version was available, but support has since been abandoned. This does not bode well for Digitalk cross-platform efforts. Digitalk has a separate GUI builder, called PARTS Workbench (bundled with Visual Smalltalk), which allows quick construct of an application.
ParcPlace and Digitalk were merged into a single company, ParcPlace-Digitalk, Inc. The future of the Digitalk product line is uncertain, and it may just be spun off back into a separate company.
IBM's version of Smalltalk, VisualAge, is comparable to Smalltalk/V with PARTS. Both of these Smalltalk's allow programmers to readily exploit machine-specific features, at the expense of some portability. IBM has adapted existing industry standards for such things as file management and screen graphics. When IBM talks, people listen, and IBM has made a substantial commitment to Smalltalk.
Java is the latest, flashiest object-oriented language. It has taken the software world by storm due to its close ties with the Internet and Web browsers. It is designed as a portable language that can run on any web-enabled computer via that computer's Web browser. As such, it offers great promise as the standard Internet and Intranet programming language.
Java is a curious mixture of C++ and Smalltalk. It has the syntax of C++, making it easy (or difficult) to learn, depending on your experience. But it has improved on C++ in some important areas. For one thing, it has no pointers, low-level programming constructs that make for error-prone programs. Like Smalltalk, it has garbage collection, a feature that frees the programmer from explicitly allocating and de-allocating memory. And it runs on a Smalltalk-style virtual machine, software built into your web browser which executes the same standard compiled Java bytecodes no matter what type of computer you have.
Java development tools are being rapidly deployed, and are available from such major software companies as IBM, Microsoft, and Symantec.
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