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Extending STIDF class : cannot creat an empty STIDF object

3 messages · Servet Ahmet Çizmeli, Edzer Pebesma

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Hello everyone,

Greetings to the r-sig-geo community.

I would like to extend the STIDF class :
setClass("newClass1",contains="STIDF",
representation(myslot="numeric"),prototype=prototype(myslot=numeric()))
setClass("newClass2",representation(first="newClass1",second="newClass1",third="newClass1"))

But a new empty newClass1 class created with the new() function does not
pass the validObject() test:
validObject(new("newClass1"))
Error in checkSlotAssignment(object, name, value) : 
		assignment of an object of class ?NULL? is not valid for slot ?time? in an
object of class ?STIDF?; is(value, "xts") is not TRUE

Tracking down the error, I could come to :
validObject(new("STIDF"))
Error in checkSlotAssignment(object, name, value) : 
		assignment of an object of class ?NULL? is not valid for slot ?time? in an
object of class ?STI?; is(value, "xts") is not TRUE

I need to be able to pass the test validObject(new("STIDF")) because my
newClass2 should be able to contain empty newClass1 slots. For now, it is
not possible!

Is this a bug?
Servet



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On 06/19/2013 06:55 PM, scizmeli wrote:
No, this is intentional.

  
    
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Thank you for your reply, Edzer,

I am not very profficient at R OO programming so If you don't mind, can you
then suggest me a way to deal with the situation? My second class sometimes
does not have data, I need to be able to create objects inherited from an
emtpy STIDF class.

any suggestions?



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