On 10-04-19 01:31 AM, BCS wrote:
Hello Justin Spahr-Summers,
On Mon, 19 Apr 2010 00:12:28 +0000 (UTC), Graham Fawcett
<fawc...@uwindsor.ca> wrote:
Hi folks,
I'd like to wrap a family of C functions that look like this:
gboolean fooXXX(arg1, ..., argN, GError** err)
Their signatures and arities vary, but they all have a GError** as
their last argument. If a function returns false, then 'err' will be
set to a relevant Error struct.
I would like to write a wrapper that would let me call these
functions sort of like this:
check!(fooXXX(arg1, ..., argN))
where the 'check' expression would be equivalent to:
GError* err;
bool ok = fooXXX(arg1, ..., argN, &err);
if (!ok)
throw new Exception((*err).message);
Does D (2.0) offer a metaprogramming technique I could use to
accomplish this -- particularly, to inject that 'err' argument into
the tail of the fooXXX call?
Thanks,
Graham
You can use some expression tuple magic to accomplish something like
that:
bool check(alias func, EL ...)() {
GError* err;
bool ok = func(EL, &err);
if (!ok)
throw new Exception((*err).message);
return ok;
}
// used like:
check!(fooXXX, arg1, ..., argN);
IIRC that should be:
check!(fooXXX, argType1, ..., argTypeN)(arg1, ..., argN);
See http://digitalmars.com/d/2.0/template.html#TemplateTupleParameter
Or you can mangel that a bit:
template check(alias func) {
bool check(EL ...)() {
GError* err;
bool ok = func(EL, &err);
if (!ok)
throw new Exception((*err).message);
return ok;
}
}
that should allow you to call it like:
check!(fooXXX)(arg1, ..., argN);
Remarkable! Thank you to everyone who responded. I can't wait to give
these a try tonight. :)
Cheers,
Graham
