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Re: IDLVM and retall [message #49999 is a reply to message #49998]

Fri, 08 September 2006 08:42

news.qwest.net
Messages: 137
Registered: September 2005

Senior Member

"Ben Tupper" <btupper@bigelow.org> wrote in message
news:4mdendF5h4mvU1@individual.net...
...
> At risk of exposing my arrested development, I harken back to exchange I
> witnessed between David and Martin Schultz eons ago. I can't remember if
> it was on the newsgroup or "off-line". But I do remember clearly that
> Martin and David leaned toward a FUNCTION event handling method rather
> than a PROcedure - the function event handling method returned 0/1 for
> fail/success. If I remember rightly, the decision was driven by the
> messaging aspect of events (or pseudo-events) and that functions, if
> nothing else, pass messages by default.
>
> Would that suffice to resolve the issue?
...
> Cheers,
> Ben

I was about to suggest the same thing. I have not needed to
do such a thing in IDL, but in creating very large applications
in Labview I always had this type of behaviour.
Every module had an "error input" structure, and if there was
an error, it just passed through (skipped) the module passing on the error,
and filling return values with defaults (like NAN or something appropriate).
One could append the whole routine call tree i guess too.
The errors were handled at a much higher level.

I have in mind something like the following:

function MyClass::f1, ev, errstruct
if n_params() ne 2 then message:"developer error: must pass errstruct"
if (errstruct.set eq FALSE) then begin
; no error passed in so perform this function
result = do_calc(errstruct)
endif else begin
; pass through errors and create default values.
result = NULL
endelse
return, result
end

pro MyClass::p1, ev, errstruct
if n_params() ne 2 then message:"developer error: must pass errstruct"
if (errstruct.set eq FALSE) then begin
; no error passed in so do this routine
do_stuff, ev,errstruct
endif
end

function MyClass::f2,ev, errstruct
OK = self->f1(ev, errstruct) ; error occurs
result = do_another_calc(ev,errstruct) ; not executed, error passed
result2 = do_yet_another_calc(result,errstruct); not executed, error
passed
result3 = do_yet_another_calc(result2,errstruct); not executed, error
passed
result4 = do_yet_another_calc(result3,errstruct); not executed, error
passed
return, result4
end

Coming out of f2 is the errstruct with a message such as:
"error divide by 1 occurred in myclass f1 function do_calc()"

It is a lot of work to retrofit a code base, but it would be easy
enough to implement when starting out.
Labview had the very nice feature of easily being able to demand that
errstruct always be passed (with a dataflow scheme you can do that).

Cheers,
bob

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[Message index]

		Re: IDLVM and retall By: JD Smith on Fri, 08 September 2006 09:35
		Re: IDLVM and retall By: JD Smith on Fri, 08 September 2006 09:30
		Re: IDLVM and retall By: JD Smith on Fri, 08 September 2006 09:26
		Re: IDLVM and retall By: JD Smith on Fri, 08 September 2006 09:12
		Re: IDLVM and retall By: news.qwest.net on Fri, 08 September 2006 09:10
		Re: IDLVM and retall By: btt on Fri, 08 September 2006 09:02
		Re: IDLVM and retall By: news.qwest.net on Fri, 08 September 2006 08:42
		Re: IDLVM and retall By: David Fanning on Fri, 08 September 2006 08:28
		Re: IDLVM and retall By: btt on Fri, 08 September 2006 07:57
		Re: IDLVM and retall By: David Fanning on Thu, 07 September 2006 21:00
		Re: IDLVM and retall By: JD Smith on Thu, 07 September 2006 15:57
		Re: IDLVM and retall By: David Fanning on Thu, 07 September 2006 12:14
		Re: IDLVM and retall By: JD Smith on Thu, 07 September 2006 11:54
		Re: IDLVM and retall By: David Fanning on Thu, 07 September 2006 06:52
		Re: IDLVM and retall By: JD Smith on Thu, 07 September 2006 01:57
		Re: IDLVM and retall By: JD Smith on Wed, 06 September 2006 23:21
		Re: IDLVM and retall By: Foldy Lajos on Wed, 06 September 2006 12:30
		Re: IDLVM and retall By: JD Smith on Wed, 06 September 2006 11:53
		Re: IDLVM and retall By: Foldy Lajos on Tue, 05 September 2006 08:31
		Re: IDLVM and retall By: David Fanning on Fri, 08 September 2006 09:48

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