How to avoid ctRegex (solved)

[cy via Digitalmars-d-learn]

At seconds PER (character range) pattern, ctRegex slows down 
compilation like crazy, but it's not obvious how to avoid using 
it, since Regex(Char) is kind of weird for a type. So, here's 
what I do. I think this is right.

in the module scope, you start with:
auto pattern = ctRegex!"foobar";

and you substitute with:
typeof(regex("")) pattern;
static this() {
   pattern = regex("foobar");
}

That way you don't have to worry about whether to use a 
Regex!char, or a Regex!dchar, or a Regex!ubyte. It gives you the 
same functionality, at the cost a few microseconds slowdown on 
running your program. And once you're done debugging, you can 
always switch back, so...

string defineRegex(string name, string pattern)() {
   import std.string: replace;
   return q{
		debug {
			pragma(msg, "fast $name");
			import std.regex: regex;
			typeof(regex("")) $name;
			static this() {
				$name = regex(`$pattern`);
			}
		} else {
			pragma(msg, "slooow $name");
			import std.regex: ctRegex;
			auto $name = ctRegex!`$pattern`;
		}
	}.replace("$pattern",pattern)
			.replace("$name",name);
}

mixin(defineRegex!("naword",r"[\W]+"));
mixin(defineRegex!("alnum",r"[a-zA-Z]+"));
mixin(defineRegex!("pattern","foo([a-z]*?)bar"));
mixin(defineRegex!("pattern2","foobar([^0-9z]+)"));

void main() {
}

/*
$ time rdmd -release /tmp/derp.d
slooow naword
slooow alnum
slooow pattern
slooow pattern2
slooow naword
slooow alnum
slooow pattern
slooow pattern2
rdmd -release /tmp/derp.d  17.57s user 1.57s system 82% cpu 
23.210 total

$ time rdmd -debug /tmp/derp.d
fast naword
fast alnum
fast pattern
fast pattern2
fast naword
fast alnum
fast pattern
fast pattern2
rdmd -debug /tmp/derp.d  2.92s user 0.37s system 71% cpu 4.623 
total
*/

...sure would be nice if you could cache precompiled regular 
expressions as files.