Re: pointer to structures

["J.D. Smith" <jdsmith(at)astro.cornell.edu>]

"Liam E.Gumley" wrote:
> 
> "J.D. Smith" wrote:
> > With time, you will get used to these semantics.  They seem arcane, but
> > eventually it becomes somewhat readable to the experienced eye.  Of course, I've
> > struggled with statements like:
> >
> >  HEADER=*(*(*self.DR)[sel[i]].HEADER)
> 
> I neglected to provide an example of why simplified pointer and
> structure referencing is desirable. Thanks for the help JD!
> 
> ;-)
> 
> Cheers,
> Liam.

But then you have to ask yourself which is worse, the confusing string above, or
the explicit:

drs_ptr=self.DR
drs=*drs_ptr
this=drs[sel[i]]
hd_arr_ptr=*this
hd=*hd_arr_ptr

repeat this about 5000 times throughout your application, and you begin to
appreciate the terse form above.  Especially if you're passing some part of the
nested data to a routine by reference... intermediate variables require you to
remember to assign them after use (everybody remember
widget_control,stash,set_uvalue=state,/NO_COPY?).  

Maybe we need a lexical parser like cdecl, to check on these for you?  A fine
programming project for an aspiring IDL programmer out there.  

JD

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