On Thursday, 8 October 2020 at 14:05:14 UTC, Andre Pany wrote:
how to this new feature interact with opDispatch? Will there be
any possibility to extract the argument names in opDispatch?
Good catch. The DIP doesn't mention opDispatch and it's probably
too late to change. I also don't really see a non-breaking way to
tell opDispatch about parameter names.
Giving opDispatch a string[] of named arguments' names (with ""
for a name-less argument) would probably do the job, but it's a
breaking change.
A different solution would be a new operator method called
`opDispatchNamed` or alike that does exactly that. However,
opDispatch is designed to be used when `c` in expr.c cannot be
resolved, where expr.c(args) is a special case where `c` happens
to be "something callable".
I'd say, the problem should be solved on a more general level:
function templates *in general* (opDispatch included) should have
a way to get named arguments' names. One possibility would be a
magic __ARG_NAMES__ that returns a compile-time string[] that
contains that names, like __FILE__ and __LINE__ at call site if
used as a default parameter. So you'd use it like:
auto opDispatch(
string methodName,
string[] argNames = __ARG_NAMES__,
T, Ts...
)(T arg, Ts args)
{
// argNames[0] will be "arg" always since it's not an
pack.
}
That way, it could be non-breaking and more useful.
