Re: [libvirt] proposal: allow use of "bool": HACKING: discuss C types
"Richard W.M. Jones" <rjones(a)redhat.com> wrote:
On Wed, Dec 17, 2008 at 09:08:36PM +0000, Daniel P. Berrange wrote:
> Ok, if you want to re-post the HACKING file also mentioning that
> 'bool' shouldn't be used in our public APIs & wire protocol,
What's wrong with using it in the wire protocol? XDR provides bool_t
(as int) and converts 'bool' in the interface definition to bool_t.
It's good to know that from portability/correctness standpoints that
would work. However, using a 32-bit "int" to transmit a single bit
of info is wasteful. How about this clarification to HACKING?
diff --git a/HACKING b/HACKING
index ba03604..ca39d61 100644
--- a/HACKING
+++ b/HACKING
@@ -115,7 +115,10 @@ standard type like int32_t, uint32_t, uint64_t, etc.
While using "bool" is good for readability, it comes with minor caveats:
- Don't use "bool" in places where the type size must be constant across
- all systems, like public interfaces and on-the-wire protocols.
+ all systems, like public interfaces and on-the-wire protocols. Note
+ that it would be possible (albeit wasteful) to use "bool" in libvirt's
+ logical wire protocol, since XDR maps that to its lower-level bool_t
+ type, which *is* fixed-size.
- Don't compare a bool variable against the literal, "true",
since a value with a logical non-false value need not be "1".
I.e., don't write "if (seen == true) ...". Rather, write "if
(seen)...".