| Re: Object within an Object's Structure [message #71366 is a reply to message #71281] |
Thu, 10 June 2010 15:22   |
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Paul Van Delst[1]
Messages: 1157
Registered: April 2002
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Senior Member |
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Paul van Delst wrote:
>
> carl wrote:
>> Hello,
>>
>> I am trying to make use of what OOP functionality IDL has, and I wish
>> to have as an object variable another object of a different type.
>>
>> Is this possible? If so, how do I specify this?
>>
>> I have an object type orbitingBody, and want to make an object
>> orbitingPair. Would this work? how would it be then coded in my init
>> function?
>>
>> pro orbitingpair__define
>> struct = { orbitingPair,
>> planet: obj_new('orbitingbody', args)
>> star: obj_new('orbitingbody', args)
>> etc...}
>> end
>
> Hmm. Why restrict yourself to only planetary and star orbiting bodies? (e.g. asteroids?
> comets?) Or even just two?
>
> Assuming your "orbitingbody" object definition contains property information about the
> type of orbiting body (i.e. planet, star, moon, asteroid, comet, etc), why not something like:
>
> pro orbitingSet__define
> void = { orbitingSet,
> n_bodies = 0L, $
> ; Container for orbiting bodies
> INHERITS IDL_Container }
> end
>
> ?
>
> You can then add as many orbiting bodies as you like:
>
> pro orbitingSet::Add, $
> obj, $ ; Object to add
> _REF_EXTRA = Extra ; Keywords passed onto IDL_Container::Add
>
> ; Add object to the container
> self->IDL_Container::Add, obj, _EXTRA = Extra
>
> ; If the object added is an orbitingBody object, increment the counter
> IF ( OBJ_ISA(obj, 'orbitingBody') ) THEN self.n_bodies++
> end
>
> This way you can store more information in your "orbitingSet" container if the need ever
> arises... and the objects you add needn't be just orbitingBody objects either.
I forgot to add a proposed get function
function orbitingSet::Get, $
_REF_EXTRA = Extra ; Keywords passed onto IDL_Container::Get
; Get the requested object reference
objref = self->IDL_Container::Get(_EXTRA = Extra)
RETURN, objref
end
(I can't recall if the _REF_EXTRA keyword just needs to be an _EXTRA or not....)
Via the IDL_Container::Get keywords, for an orbitingSet object (let's call it oSet), you
can do things like:
obj = oSet->Get(ISA='orbitingBody', COUNT=n)
if ( n EQ 0 ) then $
message, 'No orbiting bodies in set!'
You can then fancy the internals up a bit so you can return particular types of orbiting
bodies too.
Anyway....
cheers,
paulv
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