how to pass a variable name in the template in this case?

[Zhenya]

On Thursday, 2 August 2012 at 22:36:34 UTC, Andrej Mitrovic wrote:
> On 8/3/12, Zhenya <zheny at list.ru> wrote:
>> snip
>
> You mean how to extract the variable name?
>
> import std.stdio;
>
> template T(alias a)
> {
>     enum string T = __traits(identifier, a);
> }
>
> void main(string[] argv)
> {
>     char f = 'a';
>     writeln(T!f);  // writes 'f'
> }
Huh,thank you,I understood.I just thought that by default alias 
parameter is an identifier.I was surprised then I saw that 
possible to pass value of variable,which is'nt enum.Could you 
explain me why it is?