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Submitted by
P. Vijay Kumar
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ABSTRACT
Growth in Computer Technology has resulted in evolution of many programming languages. Each language was developed to overcome the drawbacks of the previous one. Each computer language comes into existence for a specific purpose. COBOL was being used for commercial applications, FORTRON for scientific applications etc.
This resulted in increase in number of programming languages, each programming language being used for a particular purpose. At this stage there came a need to develop a programming language, which could program all applications. This resulted in the development of the D programming language. D programming language is a new addition to the C family of programming languages.
D incorporates ideas and improvements from language like C++, Java and C#. Although D programming language incorporates ideas from its predecessors, it also eliminates or repairs features that were present in them. D programming language has now evolved into a major industrial force, one of the reasons being the inclusion of a new feature in it called multi-paradigm, which was not present in the earlier languages.
The D programming language, also known simply as D, is an object-oriented, imperative, multi-paradigm system programming language designed by Walter Bright of Digital Mars. It originated as a re-engineering of C++, but even though it is predominantly influenced by that language, it is not a variant of C++. D has redesigned some C++ features and has been influenced by concepts used in other programming languages, such as Java, Python, C#, and Eiffel.
INTRODUCTION
What is D?
• D is a high level programming language for applications and systems programming.
• D is a compiled language like C/C++, no byte code like in Java, no interpreter like in Perl.
• D is targeted to iron out several design flaws of C/C++. You can think of D as an upgraded
Version of C++, as the syntax is fairly similar - although it is probably more than that.
D is a general purpose systems and applications programming language. It is a higher level language than C++, but retains the ability to write high performance code and interface directly with the operating system API's and with hardware. D is well suited to writing medium to large scale million line programs with teams of developers. D is easy to learn, provides many capabilities to aid the programmer, and is well suited to aggressive compiler optimization Technology’s is not a scripting language, nor an interpreted language. It doesn't
come with a VM, a religion, or an overriding philosophy. It's a practical language for practical programmers who need to get the job done quickly, reliably, and leave behind maintainable, easy to understand code.
D is the culmination of decades of experience implementing compilers for many diverse languages, and attempting to construct large projects using those languages. D draws inspiration from those other languages (most especially C++) and tempers it with experience and real world practicality.
Who D is for?
• Programmers who routinely use lint or similar code analysis tools to eliminate bugs before the code is even compiled.
• People who compile with maximum warning levels turned on and who instruct the compiler to treat warnings as errors.
• Programming managers who are forced to rely on programming style guidelines to avoid common C bugs.
• Those who decide the promise of C++ object oriented programming is not fulfilled due to the complexity of it.
• Programmers who enjoy the expressive power of C++ but are frustrated by the need to expend much effort explicitly managing memory and finding pointer bugs.
• Projects that need built-in testing and verification.
• Teams who write apps with a million lines of code in it.
• Programmers who think the language should provide enough features to obviate the continual necessity to manipulate pointers directly.
• Numerical programmers. D has many features to directly support features needed by numeric’s programmers, like direct support for the complex data type and defined behavior for NaN's and infinities. (These are added in the new C99 standard, but not in C++.)
• D's lexical analyzer and parser are totally independent of each other and of the semantic analyzer. This means it is easy to write simple tools to manipulate D source perfectly without having to build a full compiler. It also means that source code can be transmitted in tokenized form for specialized applications.
Who D is not for?
• Realistically, nobody is going to convert million line C or C++ programs into D, and since D does not compile unmodified C/C++ source code, D is not for legacy apps. (However, D supports legacy C API's very well.)
• Very small programs - a scripting or interpreted language like Python, DMDScript, or Perl is likely more suitable.
• As a first programming language - Basic or Java is more suitable for beginners. D makes an excellent second language for intermediate to advanced programmers. The D Programming Language
• Language purists. D is a practical language, and each feature of it is evaluated in that light, rather than by an ideal. For example, D has constructs and semantics that virtually eliminate the need for pointers for ordinary tasks. But pointers are still there, because sometimes the rules need to be broken. Similarly, casts are still there for those times when the typing system needs to be overridden.
FEATURES
D is being designed with lessons learned from practical C++ usage rather than from a theoretical perspective. Even though it uses many C/C++ concepts it also discards some, and as such is not compatible with C/C++ source code. It adds to the functionality of C++ by also implementing design by contract, unit testing, true modules, garbage collection, first class arrays, associative arrays, dynamic arrays, array slicing, nested functions, inner classes, closures, anonymous functions, compile time function execution, lazy evaluation and has a reengineered template syntax. D retains C++'s ability to do low-level coding, and adds to it with support for an integrated inline assembler. C++ multiple inheritance is replaced by Java style single inheritance with interfaces and mixings. D's declaration, statement and expression syntax closely matches that of C++.
The inline assembler typifies the differences between D and application languages like Java and C#. An inline assembler lets programmers enter machine-specific assembly code within standard D code—a technique often used by system programmers to access the low-level features of the processor needed to run programs that interface directly with the underlying hardware, such as operating systems and device drivers.
D has built-in support for documentation comments, allowing automatic documentation generation.
