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Re: wrapper functions [message #50588 is a reply to message #50504]

Mon, 09 October 2006 11:03

JD Smith
Messages: 850
Registered: December 1999

Senior Member

On Fri, 06 Oct 2006 14:06:41 -0700, Dometz wrote:

> Hey Ken,
>
> Yeah, I am still trying to find a solution that will allow my to write
> more or less completely transparent wrappers. Not quite there yet... or
> in other words havent figured out to what extend this is possible or
> not.

If you're simply passing through a known number of positional
parameters, you don't need to check anything:

pro wrapper, a,b,c,_REF_EXTRA=e
routine,a,b,c,_EXTRA=e
end

should do it. The a,b,c vars will either be defined if passed, or
undefined if they weren't used.

There is a nice story in the archives about whether you can tell the
difference between an undefined variable having been passed as a
positional argument, and no argument having been passed at all
(related to the sound of one hand clapping). The answer is yes, but
since no code actually does this (certainly no RSI code), this simple
wrapper method works fine.

A more complicated case arises when you want a dynamic number of
positional arguments, for example with call_procedure. Then you are
forced to build large switch statements, etc. Often you're better off
building your own _EXTRA structures by hand in this case.

JD

P.S. See http://www.dfanning.com/tips/keyword_check.html

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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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