To avoid future problems, would you be willing to add in comparison() and
is_null() functions? I just have this bad feeling that using memcmp() could
cause issues in future code (no real idea what, more like a spidey-sense of
badness). Having a function that does comparisons that we use would make it
easy to fix things if needed.
Thanks,
Cem Karan
-----Original Message-----
From: nanomsg-bounce@xxxxxxxxxxxxx [mailto:nanomsg-bounce@xxxxxxxxxxxxx] On ;
Behalf Of Garrett D'Amore
Sent: Thursday, April 26, 2018 7:40 PM
To: nanomsg@xxxxxxxxxxxxx
Subject: [Non-DoD Source] [nanomsg] Minor forthcoming NNG change, may break
programs
I’ve been bitten too many times by C’s crummy support for strong type checks of
integer typedefs, where I pass an nng_socket type into an nng_ctx or some
other confusion. And if I’m struggling with this, I think others will to. So
I’ve decided to fix it.
The fix is that these types, which are currently all typedef’d to uint32_t,
will instead become structures containing a single member — like this:
typedef struct { uint32_t id; } nng_socket;
This value can be passed around on the stack and through return values with no
extra overhead (at least if the optimizer is turned on).
The reason this may break your programs is that the following will hold true:
a) Comparison of sockets will now need to be done either by accessing the id
field (which I’d rather you didn’t do) or memcmp. (There is little reason
normally to compare these.)
b) Checking for a “null” value (zero) means accessing the member field. Again
this is not something normal programs should need to do.
c) If you’ve actually cast these things into integer types in the past, that
won’t work. (That was always a bad idea.)
Note that assignments, passing through as is is all unaffected. The vast
majority of user code should be entirely unaffected. The huge benefit is that
the compiler now tells you when you mix up argument types or pass the wrong
type to the wrong function. The savings in confusion has the potential to be
enormous.
Please let me know if you have any concerns. I’ve made the code changes
already, and once I finish updating the documentation to reflect this I expect
to merge this back into master for NNG.
Thanks.
- Garrett
