Imagine a function like this:

void printValue(T)(string name, T value)
{
  writeln(name, " = ", value);
}

int x = 10;
printValue("x", x);

is it somehow possible to convert that printValue into a mixin or something, so I could do something like:

printValue(x);

and it will figure out the "x" part automatically?

On Sunday, 4 March 2018 at 21:03:04 UTC, JN wrote:
> Imagine a function like this:
>
> void printValue(T)(string name, T value)
> {
>   writeln(name, " = ", value);
> }
>
> int x = 10;
> printValue("x", x);
>
> is it somehow possible to convert that printValue into a mixin or something, so I could do something like:
>
> printValue(x);
>
> and it will figure out the "x" part automatically?

you can pass it by alias:

import std.stdio;

void main(string[] args)
{
    int x;
    printName!(x);
}

void printName(alias var)()
{
    writeln(__traits(identifier, var), " ", var);
}

On Sunday, 4 March 2018 at 21:12:44 UTC, arturg wrote:
>
> you can pass it by alias:
>
> import std.stdio;
>
> void main(string[] args)
> {
>     int x;
>     printName!(x);
> }
>
> void printName(alias var)()
> {
>     writeln(__traits(identifier, var), " ", var);
> }

Well, it works. But I am confused now, why. Isn't alias only for types (like a typedef)? Why can we use it for variable here?

On Sunday, 4 March 2018 at 21:48:53 UTC, JN wrote:
> On Sunday, 4 March 2018 at 21:12:44 UTC, arturg wrote:
>>
>> you can pass it by alias:
>>
>> import std.stdio;
>>
>> void main(string[] args)
>> {
>>     int x;
>>     printName!(x);
>> }
>>
>> void printName(alias var)()
>> {
>>     writeln(__traits(identifier, var), " ", var);
>> }
>
> Well, it works. But I am confused now, why. Isn't alias only for types (like a typedef)? Why can we use it for variable here?

Because it is what it is, an alias. Not a type.

It can be a type, expression or member/variable.

`printName(alias var)()` is not a great solution, eg: doesn't work
with expressions, doesn't work with variadics, introduces template
bloat.

https://github.com/dlang/dmd/pull/7821 introduces __traits(getCallerSource, symbol) which will allow what you want.

On Sun, Mar 4, 2018 at 1:53 PM, bauss via Digitalmars-d-learn <digitalmars-d-learn@puremagic.com> wrote:
> On Sunday, 4 March 2018 at 21:48:53 UTC, JN wrote:
>>
>> On Sunday, 4 March 2018 at 21:12:44 UTC, arturg wrote:
>>>
>>>
>>> you can pass it by alias:
>>>
>>> import std.stdio;
>>>
>>> void main(string[] args)
>>> {
>>>     int x;
>>>     printName!(x);
>>> }
>>>
>>> void printName(alias var)()
>>> {
>>>     writeln(__traits(identifier, var), " ", var);
>>> }
>>
>>
>> Well, it works. But I am confused now, why. Isn't alias only for types (like a typedef)? Why can we use it for variable here?
>
>
> Because it is what it is, an alias. Not a type.
>
> It can be a type, expression or member/variable.