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Re: _extra and call_method [message #42343 is a reply to message #42341]

Fri, 28 January 2005 12:38

Benjamin Hornberger is currently offline

Benjamin Hornberger
Messages: 258
Registered: March 2004

Senior Member

David Fanning wrote:
> Benjamin Hornberger writes:
>
>
>> can't keyword passing by _extra be used with call_method? I am getting
>> an error message "Keyword parameters not allowed in call" if I try to do
>> so.
>>
>> I want to write a wrapper routine which first checks if an object is
>> valid, and if yes, calls methods on it. For positional parameters, I
>> have to use "case n_params() of", which is not very nice, but for
>> keywords at least I would like to use inheritance...
>
>
> Are you *sure* you are doing this correctly? I've never
> had the least bit of trouble with it. It sounds to me
> like the method you are calling does not have the particular
> keyword you are using defined for it. Is this a spelling
> problem, perhaps?
>
> Cheers,
>
> David
>

Well, I figured out what the problem is. It's not just about
call_method, but keyword inheritance in general. If you call a procedure
and pass _extra keywords to it even though it does not accept any
keywords at all, the error occurs. Simple example:

PRO taco

print, 'Hello, world!'

END

PRO call_taco, _extra=extra

taco, _extra=extra

END

In this case, when running "call_taco", IDL issues an error because I
call "taco" with _extra keywords even though it doesn't accept any.

In my case, I want to write a general wrapper routine for several
methods of an object. For simplicity, let's say all object methods
accept one positional parameter, but zero or more keywords. What I would
like to do is:

PRO call_object, object, method, par, _extra=extra

;; method is passed as a string

IF ~obj_valid(object) THEN BEGIN
;; issue an error and more
ENDIF

call_method, method, object, par, _extra=extra

END

Now if there are any object methods which don't have any keywords
defined, the error occurs as described.

Any more hints, except defining a dummy keyword for each method?

Thanks,
Benjamin

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[Message index]

		Re: _extra and call_method By: David Fanning on Tue, 01 February 2005 07:40
		Re: _extra and call_method By: btt on Tue, 01 February 2005 07:18
		Re: _extra and call_method By: btt on Mon, 31 January 2005 07:43
		Re: _extra and call_method By: David Fanning on Mon, 31 January 2005 06:41
		Re: _extra and call_method By: btt on Mon, 31 January 2005 05:13
		Re: _extra and call_method By: David Fanning on Fri, 28 January 2005 14:21
		Re: _extra and call_method By: Benjamin Hornberger on Fri, 28 January 2005 12:38
		Re: _extra and call_method By: David Fanning on Thu, 27 January 2005 17:00

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