On 07/05/2013 05:41 PM, Max Strakhov wrote:
Suppose, in c++ i've got a variadic template function F, and i want to
convert all the arguments in some individual manner by function conv and
pass all the converted arguments as a variadic list to another variadic
template function G.
Then i just do the following:
template<typename T>
struct R;
template<typename T>
R<T>::Type conv(T&& val);
template<typename ... Args>
void F(Args&& ... args) {
G(conv(std::forward<Args>(args))...);
}
Is there any way to do the same kind of thing in D? I couldn't find any
unpacking operator or a library function to do so...
The problem is that i have to pass converted lits to a C-like variadic
function, for example printf, so it would be like:
template<typename T>
struct R;
template<typename T>
R<T>::Type conv(T&& val);
template<typename ... Args>
void MyPrintf(const char * format, Args&& ... args) {
printf(convFormat(format), conv(std::forward<Args>(args))...);
}
I hope, my point is clear enough.
Here is one that works:
import core.stdc.stdio;
import std.string;
string convFormat(string s)
{
return s ~ '\n';
}
void myPrintf(T...)(string s, T args)
{
printf(convFormat(s).toStringz, args);
}
void main()
{
myPrintf("format %d %f %c %s", 42, 1.5, 'a', "hello".toStringz);
}
Ideally, the caller of MyPrintf should not have to call toStringz on
"hello", because myPrintf is a proper D function. However, I don't know
how to manipulate args to call toStringz on string arguments.
More information is at
http://dlang.org/template.html#TemplateTupleParameter
Ali
