On Thursday, 2 October 2014 at 23:32:32 UTC, H. S. Teoh via
Digitalmars-d wrote:
Alright, today I drafted up the following proof of concept:
[...]
writefln!"Number: %d Tag: %s"(123, "mytag");
I had (amongst with others) thought about the possibility of
"ct-write".
I think an even more powerful concept, would rather having a
"ct-fmt" object dirctly. Indeed writefln!"string" requires the
actual format at compile time, and for the write to be done.
It can't just validate that *any* arbitrary (but pre-defined)
string can be used with a certain set of write arguments.
I'm thinking:
//----
//Define several format strings.
auto english = ctFmt!"Today is %1$s %2$s";
auto french = ctFmt!"Nous sommes le %2$s %1$s";
//Verify homogeneity.
static assert(is(typeof(english) == typeof(french)));
//Chose your format.
auto myFmt = doEnglish ? english : french;
//Benefit.
writfln(myFmt, Month.oct, 3);
//----
I think this is particularly relevant in that it is these kinds
of cases that are particularly tricky and easy to get wrong.
For "basic" usage, you'd just use:
writefln(ctFmt!"Number: %d Tag: %s", 123, "mytag");
The hard part is finding the sweet spot in runtime/compile time
data, to make those format strings runtime-type compatible. But
it should be fairly doable.
