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Abstract class

D. Murali

WHAT is an abstract class? ``Simply stated, an abstract class is a class that does not fully represent an object. Instead, it represents a broad range of different classes of objects. However, this representation extends only to the features those classe s of objects have in common. Thus, an abstract class provides only a partial description of its objects,'' explains Robert C. Martin in More C++ gems -- a book that compiles articles on C++ and software engineering published over a decade in C++ Report.

If you are still reading on, you would like to know that ``Because abstract classes do not fully represent an object, they cannot be instantiated.''

Does it seem a little odd to you that a class is incapable of having any instances? ``But everyday life is full of such classes,'' says Martin. ``For example, we may describe a particular animal as belonging to the class of all mammals, but we will never see an instance of the class mammal -- at least not a pure instance. Every animal belonging to the class mammal must also belong to a class which is subordinate to mammal such as mouse, dog, human, or platypus. That is because the class mammal does not fully represent any animal.''

In summary, ``In object-oriented design, we will never see an instance of an abstract class unless it is also an instance of a subordinate class. This is because the abstract class does not fully represent any object. While it is true that all objects ar e represented by a class, the converse is not true. All classes do not necessarily represent objects.''

Goes whoosh above the head?

Psychometrics

SINCE the 1970s there has been a rapid mushrooming in the output and use of so-called psychometric `tests' and profiles, in business and industry, writes Michael Williams in Test your management skills. Largely confined to managerial and professional sta ff, the instruments typically used generally fall into one of two categories: (a) Personality inventories, which are, in effect, the psychometric `heavies'. These include such well known instruments as the Myers Briggs Type; and (b) Behavioural Profiles, which are primarily instruments aimed at identifying specific preferences, behaviours and competencies -- usually those associated with managerial, professional and leadership roles.

Why use psychometric profiles? Well-constructed psychometric instruments can provide a great deal of relevant, useful information about people and their strengths and areas for development. ``In practical terms, they are best seen as an additional source of data to interviews with individuals to obtain biographical information, assessment of the individuals assessed track record and observed behaviour. The fact that the data that psychometric profiles generate is essentially relative and indicative of t he individual, shows their practical relevance and value in encouraging both assessors and respondents to explore the findings and feedback in more detail.''

Profiles are likely to be at their most helpful and useful when they are used in conjunction with other sources of data, such as development and assessment centres, so that the information they generate can be viewed, in conjunction with that produced by other assessment tools.

As in military intelligence, ``profiles provide valuable information in jigsaw forms, in that they often help to `fill in the gaps' in our understanding of how individuals behave and whether or not they are thinking, acting and working in the most approp riate and effective ways, within a role, or set of conditions.''

Ready for an assessment?

Ten commandments

WHAT does it take to be a good teacher? How does one create a fun filled environment for himself and the students? Russell Joseph in Stress free teaching, offers the following ten commandments to reduce negative stress:

* Thou shalt not be perfect or even try to be.

* Thou shalt not try to be ALL things to ALL people.

* Thou shalt leave things undone that ought to be done.

* Thou shalt not spread thyself too thinly.

* Thou shalt learn to say `No'.

* Thou shalt schedule time for thyself and support network.

* Thou shalt switch off and do nothing -- regularly.

* Thou shalt be boring, inelegant, untidy and unattractive at times.

* Thou shalt not feel guilty.

* Thou shalt not be thine own worst enemy but be thine own best friend.

Tailpiece

``You are reading my petition upside down!''

``I was only trying to put myself in your shoes.''

(Books courtesy: The British Council Library, Chennai.

e-mail: contact.chennai@in.britishcouncil.org)