Re: [Caml-list] Filename.temp_dir_name

["Sébastien Hinderer" <Sebastien.Hinderer@inria.fr>]

Dear David,

Many thanks for your response.



David Allsopp (2014/10/23 12:50 +0000):
> If you need to write code for 4.x which is also backwards compatible,
> you'll need to introduce a compatibility layer - ExtLib/Batteries
> contain examples of how to do this (especially the Unix modules in
> Batteries, which have to allow for different constructors in different
> version of OCaml sum types).
>

 
> Essentially, you'll create something like CompatibilityLayer.ml which your build system will generate as:
> 
> module Filename = Filename
> 
> for OCaml >= 4.00.0, and:
> 
> module Filename = struct
>   include Filename
> 
>   let get_temp_dir_name = (* ... code for get_temp_dir_name *)
> 
>   (* ... any other 4.00.0 functions back-ported *)
> end
> 
> for OCaml < 4.00.0. Then in each of your actual source files you'll simply add
> 
> open CompatibilityLayer
> 
> at the top. See also the bytes package in findlib >= 1.5 (doing the same thing for the OCaml 4.02 Bytes module).

Thanks for the pointers. I had a look to the different projects you
mentionned but so far I couldn't find where in the sources the
compatibility layer was defined / generated.

I mean, I understand the principle of what you explain but I'd be happy
to see a concrete example illustrating how the buildsystem generates the
appropriate files depending on the compiler version.

Would it be possible for you to show me more precisely where this is
done, plese?

Thanks,
Sébastien.

> 
> HTH,
> 
> 
> David 
>