• dsmith (13/13) Mar 23 2013 How to make workable something like this:
• Namespace (2/15) Mar 23 2013 You must specify the template type of S.
• John Colvin (14/27) Mar 23 2013 for a start, you have a foreach sitting in a struct declaration,
• Philippe Sigaud (8/21) Mar 23 2013 S is not a type here, but a template name. The type is S!(SomeArgs).

"dsmith" <dsmith nomail.com> writes:

How to make workable something like this:

struct S (T...) {
   T args;
   string arg_str;

   foreach(i; args) {
     arg_str ~ to!string(i);
   }
}

void some_function(S s) {   // here ... Error: struct S(T...) is 
used as a type
   s.args = [a, b, c];
   string args = s.arg_str;
}

"Namespace" <rswhite4 googlemail.com> writes:

On Saturday, 23 March 2013 at 17:08:27 UTC, dsmith wrote:
 How to make workable something like this:

 struct S (T...) {
   T args;
   string arg_str;

   foreach(i; args) {
     arg_str ~ to!string(i);
   }
 }

 void some_function(S s) {   // here ... Error: struct S(T...) 
 is used as a type
   s.args = [a, b, c];
   string args = s.arg_str;
 }

You must specify the template type of S.

"John Colvin" <john.loughran.colvin gmail.com> writes:

On Saturday, 23 March 2013 at 17:08:27 UTC, dsmith wrote:
 How to make workable something like this:

 struct S (T...) {
   T args;
   string arg_str;

   foreach(i; args) {
     arg_str ~ to!string(i);
   }
 }

 void some_function(S s) {   // here ... Error: struct S(T...) 
 is used as a type
   s.args = [a, b, c];
   string args = s.arg_str;
 }

for a start, you have a foreach sitting in a struct declaration, 
not in any constructor or method.

I think what you mean is:

struct S(T...) {
     T args
     string arg_str;

     this(T args) {
         foreach(i; args)
             arg_str ~ to!string(i);
     }
}

if you want the arg_str to be updated every time args are 
changed, you'll need to introduce a method (or property) for this.

Philippe Sigaud <philippe.sigaud gmail.com> writes:

On Sat, Mar 23, 2013 at 6:08 PM, dsmith <dsmith nomail.com> wrote:
 How to make workable something like this:

 struct S (T...) {
   T args;
   string arg_str;

   foreach(i; args) {
     arg_str ~ to!string(i);
   }
 }

 void some_function(S s) {   // here ... Error: struct S(T...) is used as a
 type
   s.args = [a, b, c];
   string args = s.arg_str;
 }

S is not a type here, but a template name. The type is S!(SomeArgs).
That's what you should pass to some_function:

void some_function(Args...)(S!(Args) s)
{
    s.args = [a, b, c];
    string args = s.arg_str;
}