problem with xlib binding

[Frederik Eaton]

FYI, I'm not actually running into any other problems in my
application (although as mentioned I'm only using basic
functionality). Thanks to Alastair Reid and whoever else contributed
to the bindings. Extra features such as waitForEvent are especially
appreciated. Should I submit a patch to fix the Status issue or have I
described the problem well enough?

Frederik

On Sat, May 07, 2005 at 01:05:12PM -0700, Frederik Eaton wrote:
> Hi,
> 
> Hmm, have the new xlib bindings been tested? For instance, when I run
> the following program:
> 
> ----------------------------------------------------------------
> module Main where
> 
> import Graphics.X11.Xlib
> import Graphics.X11.Xlib.Display
> 
> main :: IO ()
> main = do
>     display <- openDisplay ""
>     root <- rootWindow display $ defaultScreen display
>     getGeometry display root
>     closeDisplay display
>     return ()
> ----------------------------------------------------------------
> 
> It prints out:
> 
> xtest: user error (Error bad status 1 raised in function getGeometry)
> 
> From the code it looks like the haskell getGeometry is calling
> XGetGeometry - which has type
> 
> Status XGetGeometry(...)
> 
> - and interpreting the 1 return value as an error (via the internal
> wrapper 'throwUnlessSuccess' which takes 0 for success).
> 
> But the Xlib Programming Manual says "Some errors, such as failure to
> open a font, are indicated by return values of type Status on the
> appropriate routine ... The returned values are *zero* on failure and
> *nonzero* on success." (emphasis added)
> 
> So unless I'm really misinterpreting things, the binding to each and
> every one of the 13 functions that uses 'throwUnlessSuccess' is wrong.
> 
> Well, before I realized this I'd gone ahead and written a reasonably
> significant program against the binding assuming that at least the
> basics would work, but it seems there is some distance to go before
> the library is usable. One would think that with a "Stability:
> provisional" library every function has been run successfully at least
> once, but I can't imagine that this is the case here. Is there even a
> working Haskell equivalent of 'basicwin' from the Xlib Programming
> Manual to test things out? This would also be a helpful example for
> users.
> 
> Regards,
> 
> Frederik
> 
> -- 
> http://ofb.net/~frederik/
> _______________________________________________
> Libraries mailing list
> Libraries at haskell.org
> http://www.haskell.org/mailman/listinfo/libraries
> 

-- 
http://ofb.net/~frederik/