Hello, I have a problem I can't even understand with the code
below:
https://run.dlang.io/is/7yXAEA
import std.stdio, std.range, std.algorithm, std.traits, std.meta;
struct UNIFORM{ string name; }
struct A{
int i1;
@UNIFORM() int i2;
@UNIFORM("fuzz") int i3;
@UNIFORM int i4;
}
template getUDA(alias a, U){
static if(hasUDA!(a, U)) enum getUDA = getUDAs!(a, U)[$-1];
else enum getUDA = U.init;
}
pragma(msg, getUDA!(A.i1, UNIFORM)); //UNIFORM(null)
pragma(msg, getUDA!(A.i2, UNIFORM)); //UNIFORM(null)
pragma(msg, getUDA!(A.i3, UNIFORM)); //UNIFORM("fuzz");
pragma(msg, getUDA!(A.i4, UNIFORM)); //Error: initializer must be
an expression, not UNIFORM
struct UNIFORM2{ string name=""; }
struct B{ @UNIFORM2() int i1; }
pragma(msg, getUDA!(B.i1, UNIFORM2)); //UNIFORM("") instead if
UNIFORM(null)
//------------------------------------------------------------------------
My first question is, how to avoid that error with A.i4? Why is
there a difference between @UNIFORM and @UNIFORM(), do the first
returns a type and the later returns a value?
My second quertion is, why the UNIFORM struct with uninitialized
string producing UNIFORM(null).
How can be a difference when I say name="", and it's just the
same as the default string initializer, and then it produce
UNIFORM("")?
Thank You!
