Re: [zypp-devel] tribool ... (Fwd)

Hi! What is the reasoning behind using tribool? This seems to be the biggest headache for application developers so far... Stano Dňa Po 23. Júl 2007 17:25 Martin Vidner napísal:

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----- Forwarded message from Michael Meeks ----- Subject: tribool ... From: Michael Meeks To: zypp-devel@opensuse.org Cc: Ricardo Cruz Organization: Novell, Inc. X-Mailer: Evolution 2.6.0 Date: Mon, 23 Jul 2007 08:55:13 +0100

Hi guys,

So - I learned something fun, interesting and new this morning (at the cost of an hour or so) - it was the joys of the tribool:

if (available_obj != NULL && !available_obj->repository().info().enabled()) {

In normal usage, by the power of sequence points, this sort of thing works nicely (and indeed, it used to work before the API re-hash I think).

Unfortunately, with a tri-bool around this becomes a mess, sequence points are no longer your friend:

return false && !(zypp::ResObject::constPtr(NULL)->repository().info().enabled()) ? 1 : 0;

SEGV's immediately - try it as a return from main() ;-) it compiles to:

return tribool.operator&& (false, )

Now the fix is 'obvious' - simply split it into 2 if's, or add a '(bool)' cast to what appears to be a bool anyway ;-) but it's pretty sickeningly non-obvious to the casual user. Also, will it survive a future maintainer's desire for cleaner code without "all these odd / redundant casts in it" ?

Urgh,

Michael.

-- michael.meeks@novell.com <><, Pseudo Engineer, itinerant idiot -- To unsubscribe, e-mail: zypp-devel+unsubscribe@opensuse.org For additional commands, e-mail: zypp-devel+help@opensuse.org