On Friday, 21 November 2014 at 14:46:00 UTC, ketmar via
Digitalmars-d wrote:
On Fri, 21 Nov 2014 13:39:42 +0000
monarch_dodra via Digitalmars-d <digitalmars-d@puremagic.com>
wrote:
D has phenomenal meta programming possibilities, and I see more
and more templates taking more and more parameters. So I
thought
to myself, why not have a template builder pattern?
i did something similar in my iv.writer (ctfe format string
parser).
once i got about ten argumnets to each template (and growing),
i moved
everything to structure.
struct WrData {
... fields ...
auto set(string name, T) (in T value)
if (__traits(hasMember, this, name))
{
__traits(getMember, this, name) = value;
return this;
}
}
and then i can pass the struct around, changing only the fields
i want,
in "pseudo-functional" style:
template MyTpl!(WrData data) {
...
MyTpl!(data.set!"field0"(value0).set!"field1"(value1));
}
that was a real saver. but now i have to wait for GDC update,
'cause
2.065 frontend is not able to use structs as template args.
Hum, use a standard structure combined with CTFE to achieve the
same goal. Smart. BTW, if you use opDispatch, you could probably
have it as:
MyTpl!(data.set_field0(value0).set_field1(value1));
Which may or may not read nicer, depending on how you look at it.
With proper template overloading, you should even be able to
implement this as a backwards compatible template.