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Re: wrapper functions [message #50627 is a reply to message #50504]

Fri, 06 October 2006 08:58

David Fanning
Messages: 11724
Registered: August 2001

Senior Member

R.G. Stockwell writes:

>> "David Fanning" <davidf@dfanning.com> wrote...
>>
>>> You could, but the chance of someone passing an R
>>> vector without a G and B vector must be within the
>>> floating underflow error of zero. Why waste time
>>> coding for things that aren't going to happen? :-)
>>
>> Well, the answer to that question is:
>> If a user _can_ break it, a user _will_ break it.
>
> Hey wait, there was a smiley face at the end of it.
> Please disregard my previous message.

When I wrote that statement I realized it was totally
out of character for me (I am normally EXTREMELY anal
when it comes to programming). But, honestly, who
passes an R vector without a G and B? Absolutely
no one.

This is probably the reason these parameters are written
as optional *positional* parameters. You would be out
of your mind to write them as keywords: too much work
for the user. You might write a PALETTE keyword that
would allow you to pass a 3-by-n array of color table
vectors. That would be useful, but then the user would
probably have to figure out how to create a 3 by n array
of color table vectors and even I can't remember how to do
this half the time. :-(

For those of you who haven't read the Dimensional Juggling
Tutorial in some time, you do it like this:

palette = [[r],[g], [b]]

On the other hand, a PALETTE keyword would sure make a lot
more sense here if what we are trying to get across is
that sometimes you pass (or get) a color table and
sometimes you don't. But this would require a LOT more
programming and I would have to ask myself in the end
if making the program "better" is really worth it. In this
case, I think the answer is clearly "probably not".

Cheers,

David

--
David Fanning, Ph.D.
Fanning Software Consulting, Inc.
Coyote's Guide to IDL Programming: http://www.dfanning.com/
Sepore ma de ni thui. ("Perhaps thou speakest truth.")

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[Message index]

		wrapper functions By: Dominic Metzger on Thu, 05 October 2006 16:30
		Re: wrapper functions By: JD Smith on Mon, 09 October 2006 11:03
		Re: wrapper functions By: Dominic Metzger on Fri, 06 October 2006 14:06
		Re: wrapper functions By: Dominic Metzger on Fri, 06 October 2006 14:02
		Re: wrapper functions By: David Fanning on Fri, 06 October 2006 13:42
		Re: wrapper functions By: Dominic Metzger on Fri, 06 October 2006 13:35
		Re: wrapper functions By: David Fanning on Fri, 06 October 2006 12:47
		Re: wrapper functions By: Dominic Metzger on Fri, 06 October 2006 12:42
		Re: wrapper functions By: David Fanning on Fri, 06 October 2006 09:35
		Re: wrapper functions By: news.qwest.net on Fri, 06 October 2006 09:16
		Re: wrapper functions By: David Fanning on Fri, 06 October 2006 08:58
		Re: wrapper functions By: news.qwest.net on Fri, 06 October 2006 08:36
		Re: wrapper functions By: news.qwest.net on Fri, 06 October 2006 08:35
		Re: wrapper functions By: David Fanning on Fri, 06 October 2006 06:34

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