Compile time executable calling?

[Don]

On Friday, 12 July 2013 at 20:42:50 UTC, Tofu Ninja wrote:
> So I had an idea recently, wouldn't it be cool to have the 
> ability to call an executable at compile time and capture its 
> output. Something like the string imports but instead of 
> opening and reading a text file, it run an executable, waits 
> for it to finish, and grabs its output.
>
> It would get really cool if you could pass this executable some 
> args and then mix in its out put into your own code. It could 
> be used similarly to how CTFE are used but with out the 
> overhead of trying to compile that function and what not and 
> with out the limitations on what it can do.
>
> I could imagine all sorts of things that would be possible with 
> this that is currently not.
>
> Not sure if this is something that could be implemented easily, 
> but seems like something that could be done and something that 
> would be really cool.

I personally think it's a *horrible* idea. It's one of those 
things which looks good in small cases but doesn't scale.

Don't underestimate the fact that the compiler is a deterministic 
program at present. When compiled with the same flags, on the 
same set of source files, the results should always be the same. 
It's a classic filter program.

input -> compiler -> output

Losing that purity is a HUGE thing to give up.