Re: Passing optional parameters through a wrapper routine

["Liam Gumley" <Liam.Gumley(at)ssec.wisc.edu>]

Kenneth P. Bowman <bowman@null.edu> wrote in message
bowman-0802001505360001@bowman.tamu.edu">news:bowman-0802001505360001@bowman.tamu.edu...
> The _EXTRA keyword handles passing keyword parameters through a wrapper
> routine, but what about optional parameters?  If my wrapper for TVRD has
> one of my own (mandatory) parameters, do I have to do the following?
>
> PRO TVRD_WRAPPER, my_arg, x0, y0, nx, ny, channel, _EXTRA = tvrd_keywords
>
> CASE N_PARAMS() OF
>    1 : image = TVRD(                         _EXTRA = tvrd_keywords)
>    2 : image = TVRD(x0,                      _EXTRA = tvrd_keywords)
>    3 : image = TVRD(x0, y0,                  _EXTRA = tvrd_keywords)
>    4 : image = TVRD(x0, y0, nx,              _EXTRA = tvrd_keywords)
>    5 : image = TVRD(x0, y0, nx,              _EXTRA = tvrd_keywords)
>    6 : image = TVRD(x0, y0, nx, ny, channel, _EXTRA = tvrd_keywords)
>    ELSE : MESSAGE, 'Incorrect number of arguments.'
> ENDCASE
> ...
>
> If I just try to pass undefined arguments through my wrapper, I get
> 'undefined variable' errors.  (Is TVRD just counting the number of passed
> parameters and not checking to see if they are defined?)

Ken,

In cases like this I usually cross my arms, put my feet up on the desk, look
a person in the eye, and ask:

"How about telling me what the problem is?"

In other words, I'd like to know why you're writing a wrapper for TVRD. I've
done it myself for a number of reasons...

Cheers,
Liam.