Compile time filesystem access?

[Adam D. Ruppe]

On Monday, 30 January 2012 at 14:24:32 UTC, Manu wrote:
> I want to know if a library is present, and automatically 
> disable non-vital features if it isn't.

I'd like it too... here's what I tried. It doesn't
work, though.

===
void libraryTest(string lib)() { mixin("import " ~ lib ~ ";"); }

template libraryExists(string lib) {
        enum libraryExists =  __traits(compiles, 
libraryTest!lib());
}

void main() {
        static if(libraryExists!"arsd.cgi") {
                import arsd.cgi;
                auto cgi = new Cgi();
                cgi.write("hello w/ cgi");
        } else {
                import std.stdio;
                writeln("hello w/ stdio");
        }
}
===


That's the idea, but I couldn't get it to actually work.
Imports are apparently done by the compiler before
anything else (which makes sense, really) and that breaks
the if compiles thing; it fails before it gets there. If
you move the libraryTest inline to the compiles thing, it
never uses the lib, so that's no good either.


Alas.