Trick for function trace printing

[Dicebot via Digitalmars-d]

Noticing requests for addition of @trace attribute I decided to 
share one small snippet of mine:

=========
immutable trace =`
     import std.stdio : writefln;
     import std.string : format;

     import std.traits : ParameterIdentifierTuple;
     mixin(format(
         q{enum args = ParameterIdentifierTuple!(%s);},
         __FUNCTION__
     ));

     import std.algorithm : map, joiner;
     enum args_fmt = [args].map!(a => "%s").joiner(", ");

     mixin(format(
         q{writefln("> %s(%s)", %s);},
         __FUNCTION__,
         args_fmt,
         [args].joiner(", ")
     ));

     scope(exit)
     {
         mixin(format(
            q{writefln("< %s(%s)", %s);},
            __FUNCTION__,
            args_fmt,
            [args].joiner(", ")
         ));
     }
`;
=========

Used like this:

=========
module test;

void foo(int a)
{
     mixin(trace);

     bar(0.43, null);
}

int bar(double x, int* ptr)
{
     mixin(trace);

     return 444;
}

void main()
{
     foo(42);
}
=========

Prints

> test.foo(42)
> test.bar(0.43, null)
< test.bar(0.43, null)
< test.foo(42)

http://dpaste.dzfl.pl/3dd33973bc99

Is not optimized at all but gets job done for simple cases when I 
usually want it.

Hope it can be useful for someone else ;)