Re: Is n_params() supposed to behave this way?

[mallors(at)ips1.msfc.nasa.gov (Robert S. Mallozzi)]

In article <7ps7r7$i9p$1@nnrp1.deja.com>,
	Mirko Vukovic <mvukovic@taz.telusa.com> writes:
> Consider the following code:
> 
> pro sub1,arg1,arg2,arg3,arg4,arg5
> 
>    message,/info,string(n_params())
> 
>    return
> 
> end
> 
> pro sub,arg1,arg2,arg3,arg4,arg5
> 
>    message,/info,string(n_params())
> 
>    sub1,arg1,arg2,arg3,arg4,arg5
> 
>    return
> end
> 
> If at the command prompt I do
> 
> sub,4
> 
> IDL will print out
> IDL> sub,4
> % SUB:            1
> % SUB1:            5
> 
> In sub1 all arguments except the first one are still undefined.


Interesting, I ran across this same behavior today.  I
fixed my code by switching to N_ELEMENTS instead of
N_PARAMS.  The code is a little messier, but it works :-)

The N_PARAMS documentation is not totally clear, but 
I suppose it passes for being correct:

    "This function always returns the number of parameters 
     that were used in calling the procedure or function 
     from which N_PARAMS is called."
     
Add the caveat "even if those parameters are undefined" !

-bob



    
 
 
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Robert S. Mallozzi                                       256-544-0887
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