Language evaluation criteria. Implementation methods

Read the following words and word combinations and use them for understanding and translation of the text:

criterion (pl. criteria) – критерий

maintenance - поддержка

ease – простота

crossover – перекрестный переход

writability – легкость создания программ

domain – предметная область

realm – область действия

two-dimensional – двумерный

time-consuming - времязатратный

pure – чистый

simulation - моделирование

fetch-execute cycle – цикл выборки и исполнения

to debug – отладить

run-time – время исполнения

reliability - надежность

In order to examine and evaluate the concepts of the various constructs and capabilities of programming languages it is necessary to have a set of evaluation criteria.

Readability. Perhaps one of the most important criteria for judging a programming language is the ease with which programs can be read and understood. Before 1970 the primary positive characteristics of programming languages were efficiency and machine readability. Language constructs were designed more from the point of view of the computer than of computer users. In the 1970s, however, the software life cycle concept was developed, maintenance was recognized as a major part of the cycle. Because ease of maintenance is determined by the readability of programs, readability became an important measure of the quality of programs and programming languages. There was a distinct crossover from a focus on machine orientation to a focus on human orientation.

Writability. Writability is a measure of how easily a language can be used to create programs for a chosen problem domain. It is simply not reasonable to compare the writability of two languages in the realm of a particular application when one was designed for that application and the other was not. For example, the writabilities of COBOL and FORTRAN are dramatically different for creating a program to deal with two-dimensional arrays for which FORTRAN is ideal. Their writabilities are also quite different for producing financial reports with complex formats, for which COBOL was designed.

Reliability. A program is said to be reliable if it performs to its specifications under all conditions. Type checking is an important factor in language reliability. The earlier errors in programs are detected, the less expensive it is to make the required repairs.

Cost. The ultimate total cost of a programming language is a function of many of its characteristics. First, there is the cost of training programmers to use the language. Second is the cost of writing programs in the language. Both the cost of training programmers and the cost of writing programs in a language can be significantly reduced in a good programming environment. Third is the cost of compiling programs in the language. Fourth, the cost of executing programs written in a language is greatly influenced by that language’s design. The fifth factor is the cost of the language implementation system. Sixth is the cost of poor reliability.

Portability. This is the ease with which programs can be moved from one implementation to another. Portability is most strongly influenced by the degree of standardization of the language, which is a time-consuming and difficult process.