          PROGRAMMING IN NOTA BENE: XPL DOCUMENTS AND FILES

Anthony Woozley
Virginia
(E-mail: faraday.clas.virginia.edu)
September 30, 1991

For the last six months Itamar and I have been collaborating on a project, which is now virtually complete. Our object has been to make NB's programming and its programming language (XPL) less of a mystery than they seem to be to most users.  Making a start in XPL is neither difficult nor intimidating; and it is well worth trying for the increased power and versatility it gives in making NB do what you want it to do.  Programs can be as simple as one that will scroll the screen up or down a specified number of lines; or another that will copy a defined block of text from one file to another - and the latter can be greatly extended, e.g., to automatically copying successive entries in a bibliographical list across to IBID.  Or they can be as intricate and ingenious as those that will execute multiple commands on the command line; or will pick out from a library of programs a particular one and run it, just by means of three or four mnemonic characters entered on the command line.  The possibilities are almost unlimited.

What we have done is to create four new files, all of which are to be found in XPL.ZIP:

1. XPLBEGIN.DOC - a short and elementary introduction to XPL, in which the main program calls, functions and operators are set out, explained and illustrated.  The ground covered is the same as that in the final chapter of NB's `Customization and Programming Guide', but the treatment, it is hoped, is rather less bleak.

2. XPL-PGM.DOC - again a short document, in which the use of XPL is explained under different headings: (a) using ready made programs (and we now have over 300 of them), which you can do without ever learning anything about XPL; (b) learning XPL; and (c) the many different options for running a program.

3. XPL.DOC - a long and detailed document, which prints out at over 80 pages.  It contains just about everything that anybody could want to know about NB's programming language; and it is all explained and illustrated very clearly.  It is a goldmine of information about XPL.

4. XPLSMPLS.ZIP - a collection of programs, ranging from the very simple to the moderately complex.  Each program is in a file on its own, followed by a step-by-step analysis of the program, which discloses the structure of the program and the flow of the successive stages.  It is intended to clarify the way in which a program can be written.  At present there are some 20 programs in the collection; more may be added from time to time.

Finally, and as always, comments and criticisms from other NB users are solicited.

Tony Woozley
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