Cross module version specs

[Jonathan M Davis]

On Thursday, April 26, 2012 12:09:19 James Miller wrote:
> All I can think is that version specifiers aren't carried across
> modules

They can't be. The only time that versions apply to your entire program is if 
they're built-in or they're specified on the command line.

> which pretty much makes them completely useless unless
> you only use the built-in versions.

That's not true at all. It just means that versions are either useful for 
something within a module or they're intended for your program as a whole and 
passed on the command line (e.g. StdDdoc is used by Phobos, and it's not 
standard at all; the makefile adds it to the list of compiler flags). But yes, 
it's true that if you want to define a version in one module which affects 
another, you can't do it.

The closest that you would be able to do would be something along the lines of 
having a function in the imported module which returned the version statements 
as a string which the module doing the importing mixed in. Another option 
would be to just use static ifs, since they'd be affected by whatever variables 
or enums where defined in the imported modules. e.g.

static if(is(myVersionEnum1))
{
}
else static if(is(myVersionEnum2))
{
}

- Jonathan M Davis