Re: Just because it's a slow Thursday on this forum

[John Colvin via Digitalmars-d]

On Sunday, 7 February 2016 at 23:26:05 UTC, Andrei Alexandrescu 
wrote:
On 02/04/2016 09:46 PM, Tofu Ninja wrote:
On Thursday, 4 February 2016 at 15:33:41 UTC, Andrei 
Alexandrescu wrote:
https://github.com/D-Programming-Language/phobos/pull/3971 -- 
Andrei

People one github were asking for a dump function so they 
could do
      int a = 5;
      dump!("a"); // prints "a = 5"


Here's a working version if anyone wants it but you have to 
use it like
      mixin dump!("a");


//------------------------------------------------

mixin template dump(Names ... )
{
     auto _unused_dump = {
         import std.stdio : writeln, write;
         foreach(i,name; Names)
         {
             write(name, " = ", mixin(name), 
(i<Names.length-1)?", ":
"\n");
         }
         return false;
     }();
}

unittest{
     int x = 5;
     int y = 3;
     int z = 15;

     mixin dump!("x", "y"); // x = 5, y = 3
     mixin dump!("z");      // z = 15
     mixin dump!("x+y");    // x+y = 8
     mixin dump!("x+y < z");// x+y < z = true
}

This is useful and we should include it. How would you improve 
the code to allow dumping to a different File than stdout (e.g. 
most often stderr)? -- Andrei

Something like this?

import std.stdio : File, stderr, stdout;

template dumpTo(alias output)
if (isInstanceOf!(File, output))
{
    mixin template dumpTo(Names ... )
    {
        auto _unused_dump = {
            import std.traits : Select;
            foreach (i, name; Names)
            {
                output.write(name, " = ", mixin(name),
                    Select!(i < Names.length - 1, ", ", '\n'));
            }
            return false;
        }();
    }
}

alias dump = dumpTo!stdout;
alias errDump = dumpTo!stderr;