use template function without assignment

[JS]

On Tuesday, 30 July 2013 at 07:12:11 UTC, Namespace wrote:
> On Monday, 29 July 2013 at 23:09:20 UTC, JS wrote:
>> I have created a template Pragma that emulates pragma but 
>> better, the problem is that I have to assign it to something 
>> which is very redundant in my code:
>>
>> enum temp = Pragma!(msg)
>>
>> e.g.,
>>
>> template Pragma(alias amsg)
>> {
>>    string Pragma(string file = __FILE__)
>>    {
>>        pragma(msg, amsg);
>>        return "";
>>    }
>> }
>>
>> When I try to use void instead of string and do something like
>>
>> Pragma!(msg)
>>
>> I get an error that the template has no effect. It does have 
>> an effect but what it is complaining about is exactly what I 
>> want.
>>
>> I've tried all kinds of combinations(mixins work but I then 
>> can't ise __FILE__) and nothing works. Maybe someone has an 
>> idea.
>
> You could call your template in a static CTor:
>
> ----
> import std.stdio;
>
> template Pragma(alias amsg)
> {
>     void Pragma(string file = __FILE__)
>     {
>         pragma(msg, amsg);
>     }
> }
>
> static this() {
> 	Pragma!("foo")();
> }
>
> void main()
> {
> 	writeln("Hello world!");
> }
> ----
>
> Maybe this helps?

This is useless. It's goal is to debug templates and essentially 
just wrapping pragma to supply the __FILE__ info automatically.

e.g., instead of having to do

pragma(msg, __FILE__~amsg);

I want to do Pragma!(amsg);

where Pragma custom formats the error or info message with the 
location where the message was initiated.

Sticking it in a ctor will only print a message from that 
location.