"Rob Preece" <Rob.Preece@msfc.nasa.gov> wrote in message
news:Rob.Preece-1104021521040001@biggamma.nsstc.nasa.gov...
>
> I have a *very* good reason for doing it this way (otherwise, why
> bother! ;) I have a set of keywords to pass on to an embedded plot
> routine, and I can't know at the time what their values will be. I
> have a plot zooming function in a widget (object) that simply calls
> the object's 'PLOT' method, passing new x and y ranges. The plot
> method does some stuff, and then hands it all off to the IDL
> (direct) PLOT routine, adding in the 'XRANGE' and 'YRANGE' keywords
> so that they can be overridden when the 'ZOOM' method is
> invoked. Very much like 'test1' in my sample code. Since I followed
> the documentation as Mark H. mentioned, is this a valid bug in IDL?
> How to proceed?
Yes it's a bug. Report it to IDL.
Re the need to do it this way, if you're passing specific keywords
then you don't *need* to use inheritance. Eg this...
PRO test1, _REF_EXTRA=extra
test2, INDGEN (10), _EXTRA = ['TITLE','XTITLE','YTITLE', 'XRANGE']
END
...can be written...
PRO test1, TITLE=title, XTITLE=xtitle, YTITLE=ytitle, XRANGE=xrange
test2, INDGEN (10), TITLE=title, XTITLE=xtitle, YTITLE=ytitle, $
XRANGE=xrange
END
(I note that your original test1 was a little more complicated than
the one I have written. Was there a reason for that?)
If you want to direct different keywords to different routines you can
do this.
PRO test1, TITLE=title, XTITLE=xtitle, YTITLE=ytitle, XRANGE=xrange
test2, INDGEN (10), TITLE=title, XTITLE=xtitle,
test3, YTITLE=ytitle, XRANGE=xrange
END
or even
PRO test1, TITLE=title, XTITLE=xtitle, YTITLE=ytitle, XRANGE=xrange, $
_EXTRA=extra
test2, INDGEN (10), TITLE=title, XTITLE=xtitle,
test3, YTITLE=ytitle, XRANGE=xrange
test4, _EXTRA=extra
END
Defaults can be supplied and overridden for explicit or inherited
keywords, eg:
PRO test1, KEY1=key1, _EXTRA=extra
if n_elements(key1) eq 0 then key1 = 33
test2, indgen(10), KEY1=key1, KEY2=33, _EXTRA
END
The default for key1 is obvious, What's not so obvious is that if I
call
IDL> test1, KEY2=66
then this value is passed to test2, overriding 33.
Warning: if you use this last technique with IDL 5.4 you must use
inheritance by value not reference because there was a bug in 5.4.
Of course with the different bugs in different versions you may well
decide to leave your code as it is and stick with 5.4!
--
Mark Hadfield
m.hadfield@niwa.co.nz Ka puwaha et tai nei
http://katipo.niwa.co.nz/~hadfield Hoea tatou
National Institute for Water and Atmospheric Research (NIWA)
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