| Re: Object as a member to object/class [message #58698 is a reply to message #58696] |
Tue, 12 February 2008 14:10   |
ben.bighair
Messages: 221
Registered: April 2007
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Senior Member |
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On Feb 12, 3:45 pm, Sven Utcke <utcke+n...@informatik.uni-hamburg.de>
wrote:
> Hi,
>
> I'm plainly too stupid for the following: I would like to have an
> object as a member to a second class. I.e. I have something like
> this:
>
> PRO MODBUS__DEFINE
> struct = { MODBUS, Host:"hasgkssccdkal.desy.de", Port:502, tid:0L }
> END
>
> and, later on,
>
> PRO GKSSBC__DEFINE
> struct = { GKSSBC, Con:Obj_New(), addr:'4020'XL, Factor:1.0, Steps:200, Micro:6 }
> END
>
> Now, I would _like_ to do something like
>
> FUNCTION GKSSBC::INIT, addr = addr, factor = factor, con = con
> IF KEYWORD_SET(addr) THEN self.Addr = addr ELSE self.Addr = '4020'XL
> IF KEYWORD_SET(factor) THEN self.Factor = factor ELSE self.Factor = 1.0
> IF KEYWORD_SET(con) THEN self.Con = con ELSE self.Con = obj_new("modbus")
> return, 1
> END
>
> But even just doing
>
> FUNCTION GKSSBC::INIT
> self.Con = obj_new("modbus")
> return, 1
> END
>
> does't wor at all in IDL 6.4 (it results in something like:
>
> % Object reference expression not allowed in this context: <OBJREF
> (<ObjHeapVar38(MODBUS)>)>.
> % Execution halted at: GKSSBC::INIT 13
> /afs/desy.de/user/u/utcke/src/Modbus/gkss9100C.pro
> % OBJ_NEW
> % $MAIN$
>
> So how does this _really_ work?
Hi,
No such thing as too stupid. Learning curves can be twisted, that's
all. My first thought is that MODBUS does not have an MODBUS::INIT
method since you don't show it. Can you successfully instantiate a
MODBUS object on its own? Like...
IDL> obj = OBJ_NEW("MODBUS")
On a different note, you might find it fruitful to look at David
Fanning's excellent description of when to use KEYWORD_SET vs.
N_ELEMENTS. http://www.dfanning.com/tips/keyword_check.html
Cheers,
Ben
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