[m-dev.] call for volunteers: get_environment_var_map

[Julien Fischer]

Hi Zoltan,

On Wed, 18 Aug 2021, Zoltan Somogyi wrote:

> At the moment, mmc --make passes around I/O states
> so it can look up the values of environment variables
> that may contain options. I would like to limit the use
> of I/O states as much as possible, so I would like to read in
> the values of all the environment vars once at the start,
> so that all later lookups could be done without access
> to an I/O state.
>
> The attached diff, of which I committed only the options_file.m
> part, implements the reading-in process for C, but the overall
> approach is viable only if there are implementations for C# and
> Java as well. I added a draft of the Java version based on an
> Oracle documentation page
> https://docs.oracle.com/javase/tutorial/essential/environment/env.html,
> but haven't tested it, and I don't know enough about C# to do
> that version.
>
> Would anyone like to put their hand up to do the C# and Java
> versions?

Sure, I'll add them.

Rather than putting this facility in the compiler, we should consider
adding it alongside the other predicates that deal with the environment
in the io module, e.g. as io.get_environment/3.

Julien.