Because D currently doesn't support RAII using named parameters
like in Python I tried the following.
Say I have an aggregate
class C { int x,y,z,w; }
or similarly
struct C { int x,y,z,w; }
I know define a generic _free_ function
ref T set(string member, T, U)(ref T a, in U value) if
(isAggregateType!T &&
hasMember!(T, member))
{
mixin(`a.` ~ member ~ ` = value;`);
return a;
}
which I want to use for flexible initialization of several
members at once.
However using this function through UFCS
auto cx = new C().set!"x"(11);
fails as
algorithm_ex.d(1257,17): Error: template algorithm_ex.set cannot
deduce function from argument types !("x")(C, int), candidates
are:
algorithm_ex.d(1242,7): algorithm_ex.set(string member, T,
U)(ref T a, in U value) if (isAggregateType!T && hasMember!(T,
member))
Instead I have to use
auto c = new C(); set!"x"(c, 11);
which is not as elegant.
Why doesn't UCFS work here and is there a solution using DMD git
master?
Further Is there a cleverer way to do this without resorting to
mixins?
This old post
http://forum.dlang.org/thread/mailman.2966.1301533296.4748.digitalmars-d-le...@puremagic.com
talks about opDispatch() but, to my knowledge, it requires the
aggregate to have extra members doing the initialization.
I want this because I've identified in some parts of my code that
I have large structures were only a few of the elements are
initialized to non-default values.
