| Re: qualifying object classes on the fly [message #83630] |
Fri, 15 March 2013 11:41 |
Michael Galloy
Messages: 1114
Registered: April 2006
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Senior Member |
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On 3/15/13 11:00 AM, kagoldberg@lbl.gov wrote:
> Is there an accepted method, or an available function, for determining of an object class exists. I'd like to declare an object with the class specified as the argument to obj_new(), and if it fails to find a known class, have the object return as !null or obj_new(). This is the behavior I would like.
>
> o = OBJ_NEW('testclass', /RETURN_NULL_ON_FAIL)
>
> Currently, asking for a non-existent class breaks the program. Some part of me thinks it would be too inelegant to use CATCH for something like this.
>
> Alternately, is there a routine like this:
> result = TEST_OBJ_CLASS('testclass') ?
>
> Thanks
>
Inelegant or not, I think CATCH is the solution for this:
function test_class, classname, _extra=e
compile_opt strictarr
catch, error
if (error ne 0L) then begin
catch, /cancel
return, obj_new()
endif
return, obj_new(classname, _extra=e)
end
Mike
--
Michael Galloy
www.michaelgalloy.com
Modern IDL: A Guide to IDL Programming (http://modernidl.idldev.com)
Research Mathematician
Tech-X Corporation
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