Portable keyboard signal handling

[Robert Dockins]

On Friday 01 September 2006 03:55, Simon Peyton-Jones wrote:
> | Indeed.  I had to browse the source after finding that the Haddock
> docs are
> | essentially useless.  I do have to say, one nice side effect of using
> darcs
> | is that one can simply point one's browser at the source repository to
> peruse
> | the code.  I've bookmarked http://cvs.haskell.org/darcs   :-)
>
> Good idea.  Could you help us improve the documentation by sending darcs
> patches with Haddock docs in them?  Not necessarily comprehensive: at
> least recording the bits you discovered, and wished had been in the docs
> in the first place.

Well, here's the odd thing; there ought to be meaningful haddock docs already.  
By that, I mean that there are data declarations and type signatures and such 
already in the file that haddock should be picking up on.  However, the whole 
file is protected by a big ifdef:

module GHC.ConsoleHandler
#if !defined(mingw32_HOST_OS) && !defined(__HADDOCK__)
	where
import Prelude -- necessary to get dependencies right
#else /* whole file */
	( Handler(..)
	, installHandler
	, ConsoleEvent(..)
	, flushConsole
	) where

..... rest of file ....


It looks like the definitions in the file _should_ be visible to haddock, but 
for some reason they aren't.  So, this looks like a build system problem of 
some sort to me.  I don't know how the docs are built, so I'm not sure how 
one would go about fixing this.


> Thanks!
>
> Simon


Do you have any ideas about the original question?  It looks like RTS trickery 
is necessary to get this right in general.  Looking at this file in a little 
more detail, I see calls to 'rts_installHandler', which is surely why this 
file is in the GHC.* namespace.

Perhaps 'withControlCHandler' or something like it should go into the 
libraries somewhere?  I'm not sure this is a function that can be provided 
without RTS assistance.  It also seems to be about the maximum intersection 
of the capabilities of Posix signals and of the Win32 console events system.


-- 
Rob Dockins

Talk softly and drive a Sherman tank.
Laugh hard, it's a long way to the bank.
       -- TMBG