On Mar 22, 2010, at 5:35 PM, Grant Olson wrote:

> 
> I'm doing something weird here and I'm thinking there has to be a better
> way.
> 
> I've got a configuration file that's a .ml file.  And I do want it to be
> an .ml file that gets included at compile time, not some .txt config
> file that gets read in at runtime.  I'm building two different versions
> of my app, with two different configurations.

Why ? Why ? Why not having your app configurable with a txt file
or some command line flags like every other programs ?

> 
> Basically, I want to do the same thing as a C #ifdef:
> 
> #ifdef VERSION2
>   ... include version one
> #else
>   ... include version two
> #endif

People use that because they want to do different things depending on the architecture, or
if some dependencies are present or not. Do you have the same requirement here ?

> 
> And then the two different builds link in two different object files
> that have the same interface, creating the two different versions of the
> app.
> 
> At first I thought I could write out the "module" and "module type"
> stuff manually, giving the same module name in two differently named
> files.  But this of course creates a sub-module that isn't bound to the
> right namespace, and linking fails.
> 
> What I'm doing now is using the -impl flag.  I've got two files:
> config.ml, and config.alt.  The second version builds with "-impl
> config.alt" in the list of files passed to ocamlopt instead of "config.ml"
> 
> This works, but it just seems wrong.  Is there a better way for me to do
> this?
> 
> -Grant
> 
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