Allan Schaffer (aschaffe)
Thu, 18 Nov 1993 18:00:18 -0800
Forwarding to info-performer ...
Allan
--- Forwarded mail from David Cooper <davec++at++division.demon.co.uk>
I have just made the same mistake twice and wasted a few days when I could
least afford it. Hopefully by discussing this now I'll stop someone else
from doing the same.
My problem was with the commands
pfSegIsectNode and
pfSegIsectGSet,
if you will be using these in the near future read on.....
These commands can appear similiar to the unwarey: functionally they are alike,
the manual entries are almost identical, they take the same number of
parameters
, the parameters have the same names and definitions, BUT parameters 4 & 5 are
REVERSED between the functions. The mode and mask fields switch around between
the Node and GSet variations. Even worse, as these fields are just bitmasks the
compiler will not flag the error, nor will the command when it is executed. All
that will happen is that the command will work but not quite the in way
expected, or even worse it will work correctly now but will stop working a
few months from now when some other apparently unrelated change is made.
My Case
-------
I started off by using pfSegIsectNode but decided to switch to the GSet
variation. A quick skim through the manual entry left me convinced that it
was identical to the other except operating at a lower level, allowing more
control. So I just copied the previous command changing the name and some of
the parameters but NOT the order. It took me two days and a mail message to
this mail board before I was told that my parameters were wrong. Such a stupid
mistake made me feel very foolish and permanently ingrained the order into my
memory. Yesterday I started using pfSegIsectNode again and again things did
not work quite as expected. Imagine my surprise when I discoverd that I had the
parameters wrong again. It was only then I read the manual entries closely,
and discovered this subtle difference. Another day wasted !
SGI
----
How about a mention in the manual that points out this difference. I
am sure that I am not the only one to have experienced this problem and it is
very easy to do.
David Cooper
Division Ltd
UK
--- End of forwarded mail from David Cooper <davec++at++division.demon.co.uk>
-- Allan Schaffer Silicon Graphics aschaffe++at++sgi.com
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