Re: [Gtk2hs-devel] Flags class and fromFlags, toFlags bug

[Duncan C. <dun...@wo...>]

On Mon, 2005-05-09 at 08:55 +0100, Axel Simon wrote:
> > so it goes wrong. c2hs generates that enum instance code and provides
> > C2HSMarsh.extractBitMasks which has the same bug. So it's a c2hs bug
> > too. So toFlags/C2HSMarsh.extractBitMasks must have gone unused for the
> > last 5 years!
> 
> Oh dear, that's probably my fault since I suggested adding the Flags to
> Manuel. How scary that nobody ever used functions that return flags...

Well I've fixed it like so (it's comitted to CVS already):

toFlags :: Flags a => Int -> [a]
toFlags f = testBits f 1
  where testBits f n
          | f == 0        = []
          | f `testBit` 0 = toEnum n : testBits (f `shiftR` 1) (n `shiftL` 1)
          | otherwise     =            testBits (f `shiftR` 1) (n `shiftL` 1)

Which seems ok to me and seems to work. Perhaps we should tell Manuel.

Actually, I don't suppose it's so suprising the no-one used a function
that returns flags. There are actually very few of them it Gtk. I know
I've never used any function which uses flags. And I guess that usually
they are attributes that you set but never need to get.

And other comments on your TODO list items? I recall that we hadn't
quite come to a conclusion about the Pixbuf stuff or onExposeRegion.

Duncan