Category : Dbase (Clipper, FoxBase, etc) Languages Source Code
Archive   : FAQ.ZIP
Filename : FAQ100.1

 
Output of file : FAQ100.1 contained in archive : FAQ.ZIP
Archive-name: clipper-faq/part1
Last-modified: 1992/12/01
Version: 1.00


FREQUENTLY-ASKED-QUESTIONS (FAQ) LIST FOR CLIPPER
PLEASE SEND SUBMISSIONS TO [email protected]


Release 1.00, 1 December 1992


This document as a whole is copyrighted (c) 1992 by Mark W. Schumann.
Some portions of this document may be copyrighted by the individual
authors. Use and redistribution of this document throughout electronic
text services is welcomed as long as no fee is charged for such
distribution aside from normal connect charges associated with use of
said electronic text service. This work is a free service, copyrighted
not to limit its use but to prevent OTHERS from restrictively
copyrighting it.


WARRANTY DISCLAIMER
(to keep my lawyer happy)

Because this document is provided free of charge, there is no warranty
for the document, to the extent permitted by applicable law. Except when
otherwise stated in writing the copyright holders and/or other parties
provide the document "as is," without warranty of any kind, either expressed
or implied, including, but not limited to, the implied warranties of
merchantability and fitness for a particular purpose. The entire risk as
to the quality of this document is with you.

In no event unless required by applicable law or agreed to in writing
will any copyright holder, or any other party who may modify and/or
redistribute the document as permitted above, be liable to you for damages,
including any general, special, incidental or consequential damages arising
out of the use or inability to use this document (including but not limited
to loss of data or data being rendered inaccurate or losses sustained by
you or third parties).

Any contributions made by others to this document have been
acknowledged. Specific references, where available, are noted with an
octothorpe (#) at the extreme left edge of the document. Commercial
products, retailers, or distributors mentioned here are not necessarily
endorsed by me or any other particular party.

I will continue updating this list from time to time, generally on the
first weekend of every month. It will be posted to the Bitnet lists
DBASE-L@NMSUVM1 and CLIPPER@BRUFPB, the Compuserve CLIPPER Forum
Section 17 (Misc./Short Term), the Usenet newsgroup
alt.msdos.programmer, the "Clipper Database Support" echo on GT Power,
and the CLIPPER echo on Fidonet, as well as whatever Clipper-oriented
bulletin boards catch my attention.

You may also request updates to this listing by e-mail to:

Usenet: [email protected]
Bitnet: mark%whizbang.wariat.org@cunyvm
Compuserve: 73750,3527
Fidonet: MARK SCHUMANN on PC-Ohio (1:157/200)

Please send any candidates for "Frequently Asked Questions" (or answers)
to the same e-mail address.


======================================================================
LICENSING ISSUES.
======================================================================

Q. We're thinking of leaving DBU on our client's machines for
support purposes; we don't want to have them buy dBase.
Is it legal to do so?

A. According to Craig Ogg of CA/Nantucket, "The code is free to be
distributed, even if it is modified, as long as it isn't
charged for." So go ahead!

# Compuserve NANFORUM Section 1, #141799, 5-Jun-91.

----------------------------------------------------------------------

Q. My company wants to save money by putting our three Clipper
development machines onto a LAN. This way we can buy one
copy of Clipper 5 for the three programmers, right?

A. Wrong. The CA/Nantucket license allows the product to be used
on a network, but there still must be one license for each
developer. (Complain to CA/Nantucket if you don't like it.)


======================================================================
CLIPPER BUGS, ANOMALIES, DEFICENCIES, AND/OR SURPRISES.
======================================================================

Q. I keep getting financial arithmetic results that don't add up
exactly. From time to time my calculations are off by a few
cents but I'm sure there is nothing wrong with my code. What's
the deal?

A. This is because Clipper doesn't store your numeric values as
decimal numbers. Instead, it uses Microsoft's version of 32-bit
floating point representation, which is logarithmic. There is
naturally some rounding involved, as most decimal numbers cannot
be represented as a sum of powers of two. This rounding error
accumulates in your calculations and eventually appears as a lost
(or gained) penny or two. (This is the same reason why FORTRAN
programmers never do financial calculations with DOUBLE PRECISION
values.)

There is not very much you can do about "decimal creep" unless you
want to do all your own math routines on strings or in whole
numbers.

I asked Brian Russell of CA/Nantucket's development team about this
at the Fall 1992 DevCon and he said there were really no plans to
"fix" this in the near future, but it is theoretically possible
to hack some internals to achieve the same result.

----------------------------------------------------------------------

Q. Why is "ABCDEF" = "ABC" turning up TRUE in my code?

A. The single equal sign operator (=) is not what you expect.
If you have SET EXACT OFF (the default) then string comparisons
only check as far as the length of the right-side value.
If you want an exact match, then you should use the double-equals
operator (==) instead. Many programmers forget about it on
purpose and just SET EXACT ON, but there are times (such as
looking up a partial key) when the "fuzzy match" is useful.

----------------------------------------------------------------------

Q. What is this "magic number" problem in Clipper Summer '87?

A. The "magic number" is a bug in CLIPPER.LIB's index functions
which causes the system to hang under certain combinations of
(a) record length, (b) index key length, and (c) number of
records in file.

I have one report indicating that this occurred when an index
had key length 10 and there were either (2 ^ 7 * 3) or (2 ^ 7
* 3 ^ 2) records in the database file.

This only occurs when you are linking with the CLIPPER.LIB
which is time-stamped 2:00am. Nantucket fixed the bug and
released a new CLIPPER.LIB which is time-stamped 4:00am.
You can request a free update diskette from CA/Nantucket, but
my information says that they will only do this for people
who have paid for extended support.


======================================================================
CORPORATE ISSUES AND FUTURE VERSIONS OF CLIPPER.
======================================================================

Q. Is it true that Nantucket was bought by Computer Associates?

A. Such an agreement was announced on the 6th of May 1992 and has
been consummated. The Clipper product is now known formally as
"CA-Clipper."

----------------------------------------------------------------------

Q. What is this Aspen thing? Visual Objects?

A. "Aspen" is the not-so-secret code name for an exciting project
on which the Nantucket developers were working before the CA
acquisition. The product that will eventually, perhaps in 1993,
come out of the Aspen project is called "CA-Visual Objects," or
VO for short. VO will first be released for the Microsoft Windows
environment, but will eventually be ported to other graphical
systems.

VO will be more fully object-oriented than the current release
of Clipper. VO features a slick development environment (which
somewhat resembles that of Borland's C++ for Windows), including
an incremental compiler. The compiler itself will support a hybrid
of xBase and C/C++ techniques; it will, for example, generate
straight machine code instead of pseudo-code if you supply proper
typing information or if it can figure this out from context.

Programs developed with the VO technology will have use of the
full range of graphical elements available in each operating
environment it supports.

CA has stated that the first release of CA-Visual Objects will
actually be called "CA-Visual Objects for Clipper," which seems
to imply that there will be a "VO for COBOL" and other languages.
How they will separate the particular language from its
implementation in a VO environment remains to be seen.

Note that CA has made no formal product announcement for VO.

----------------------------------------------------------------------

Q. What is Clipper 5.2?

A. Clipper 5.2 (actually "CA-Clipper 5.2" these days) is a bug-fix
release that will also include, according to CA:

* New RDDs (Replaceable Database Drivers) for NTX (native Clipper),
MDX (dBASE IV), FoxPro, and Paradox file formats;

* Published API for Replaceable Database Drivers and Virtual
Memory Management;

* Improved documentation;

* Upgraded EMS support; and

* RSIS (Relocateable Screen Interface Specification) compliance.

Clipper 5.2 will be available to existing registered Clipper users
through dealers at US $149.00.

----------------------------------------------------------------------

A. What is Clipper 5.X?

Q. Clipper 5.X will follow 5.2, but it has not been specified in
detail and no release date is set. Its key improvement over 5.2
will be that user-defined objects will be supported directly rather
than requiring a third-party library such as Class(y), Superclass,
or o:Clip.

----------------------------------------------------------------------

Q. What is this Statement of Direction thing?

A. Please request a hardcopy from Steve Silverwood at Computer
Associates, whose Compuserve address is 76703,3035. It can also
be downloaded from Compuserve's CLIPPER forum, Section 0. The
file name, depending on your preferred file format, is SODTXT.ZIP
(ASCII), SODRTF.ZIP (Rich Text Format), or SOD.ZIP (Word for
Windows).

----------------------------------------------------------------------


  3 Responses to “Category : Dbase (Clipper, FoxBase, etc) Languages Source Code
Archive   : FAQ.ZIP
Filename : FAQ100.1

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