| Re: Saving / Restoring Objects [message #35031] |
Fri, 09 May 2003 12:33  |
JD Smith
Messages: 850
Registered: December 1999
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Senior Member |
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On Fri, 09 May 2003 06:33:06 -0700, David Fanning wrote:
> mfeldt (mfeldt@mpia.de) writes:
>
>> trying myself and surfing the web I find a lot of remarks how useful
>> it is to save and restore idl objects. However, for me it doesn't
>> seem to work - am I doing something wrong here? Basically what I do is
>> this:
>>
>> IDL> a=obj_new('fancy_object')
>> % Compiled module: FANCY_OBJECT__DEFINE. ;; ;; this compiled my object
>> with lots of functions etc.. ;; IDL> a-> set,'Debug',1 ; internal
>> variable access... ;; ;; many more of those may go here ;; ;; then:
>> IDL> save,a,file='test.sav'
>>
>> IDL> exit
>>
>> ;; now a new session
>>
>> IDL> restore, file='test.sav'
>> IDL> help,a,/obj
>> ** Object class FANCY_OBJECT, 0 direct superclasses, 0 known methods
>>
>> ;; i.e. the object seems to be there, but all information on it and
>> all methods are lost... I also tried compiling the related code first,
>> but no use...
>>
>> Is there any way to make this work??
>
> I don't think the methods are "lost", they just haven't yet made
> themselves known to IDL. (Although I would have thought compiling the
> routines should have worked and would be essential--you use
> Resolve_Routine, right?--to restore the object properly) In any case, I
> would feel free to use your restored object as normal and see what
> happens.
>
> I guess whether the methods can be "found" will depend to some extent on
> how you are naming the methods and the files that contain them. But this
> SAVE/RESTORE method certainly works for objects.
>
>
If all your methods are in the fancy_object__define file, then you'll have
to explicitly compile this file. This is because the saved object
implicitly contains the class definition (but no methods). Hence, IDL
never feels the need to run the class definition procedure at the end of
fancy_object__define.pro, and your methods defined there remain hidden.
This problem has been discussed in great detail over the years, and David
even has a topic on his site outlining a workaround.
One alternative easy option is to make a separate file for each method,
e.g. fancy_object__init.pro. This gets fairly distracting fairly
quickly, so most people prefer the resolve_obj method.
JD
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