Re: [Caml-list] Building multiple configurations?

[Yoann Padioleau <padator@wanadoo.fr>]

On Mar 22, 2010, at 6:32 PM, Grant Olson wrote:

> 
> On 3/22/2010 9:13 PM, Yoann Padioleau wrote:
>>> 
>>> 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 ?
>> 
> 
> Because it's an elaborate configuration.  

Apparently it's a boolean since you support only 2 different configs ...


let config1 = {
 field1 = 1;
 field2 = true;
}

let config2 = {
 field1 = 2;
 field2 = true;
}

(* settable via command line or config file *)
let config = ref true 

let current_config () = 
 if !config then config1 else config2

...

let main = 
 let args = [
 "-config1", Arg.Set config, "";
 "-config2", Arg.Clear config "";
 ]
 in
 Arg.parse ... blablabla


> I don't want to write an
> equally elaborate parser when I've already got ocaml to do that for me.
> I'd rather get a compile-time error than a runtime error if the syntax
> is bad.  And the app isn't designed to be user-configured.
> 
>>> 
>>> 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 ?
>> 
> 
> They also use it for things like debug/release build.  But I suppose you
> could say that the two configurations have totally different
> dependencies for these purposes.
> 
> I know what I'm doing is a little weird.  But I have my reasons for
> wanting to do it this way.
>