Set variable at compile time

[Craig Dillabaugh]

On Wednesday, 30 October 2013 at 20:19:11 UTC, Adam D. Ruppe
wrote:
> It won't really work on the command line alone, but the way I 
> do it is a two step thing. First, make the thing use a config 
> module:
>
> import myproject.config;
>
> alias Thing Thing_Impl!dim;
>
> then you go ahead and use Thing, which is instantiated with the 
> dimension. Then the user makes a file:
>
> module myproject.config;
>
> enum dim = 10; // or whatever
>
>
> and compiles it all:
>
> dmd main.d yourlib.d config.d
>
> and it works out. They can swap out config.d for other files 
> with other values and definitions on the command line to 
> customize it.
>
>
> It would also be possible to provide a default if you go with 
> the whole library route, compiling the default into the .lib 
> and giving the default in the project include path, both of 
> which would be overridden by the user's explicit config source 
> file on the command line.
>
>
>
> So not as simple as -Ddim=10, but gets the job done. You can 
> also use this technique with static if to version stuff out 
> they don't want and other similar tasks; I actually like it 
> better than -version for the most part.

This should work for what I want, and I was thinking of something
along these lines, but was hoping there might be a simpler
solution.

Craig