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objective-cpointersreferencemacrubynsrange

MacRuby pointers and Obj-C function returning a value by reference

I am trying to implement the following method of NSAttributedString in Macruby:

  • (id)attribute:(NSString *)attributeName atIndex:(NSUInteger)index effectiveRange:(NSRangePointer)aRange

As by definition, it Returns the value for an attribute with a given name of the character at a given index, and by reference the range over which the attribute applies.

OK, so I need a pointer to NSRange, which I set up as follows:

range=Pointer.new("{_NSRange=QQ}")[0]

It seems to be fine as range.class => NSRange.

However, when I execute the method: 

font=txtStor.attribute(NSFontAttributeName,atIndex:index,effectiveRange:range)

my range is always #<NSRange location=0 length=0>. Also, p range gives me #<NSRange location=0 length=0>.

Any ideas how to implement this correctly?

Solution

  • I was given the solution by Watson at the MacRuby-devel mailing list. I should have written my code like that:

     range=Pointer.new(NSRange.type)
 #though range=Pointer.new("{_NSRange=QQ}") would also work

    then, as I had before

    font=txtStor.attribute(NSFontAttributeName,atIndex:index,effectiveRange:range)

    and if needed I could dereference the range by range[0].