Inner modules / namespaces

[Bruno Medeiros]

Bill Baxter wrote:
> One thing I find I keep wishing D had was a way to make a distinct 
> namespace inside a file.  This would make it possible to group bits of 
> functionality into namespaces without having to break each one out into 
> a separate file.
> 
> I think the most natural way to do this would be to allow inner modules. 
>  These modules would not be directly importable from outside but would 
> be accessible from outside if public.
> 
> Basic example:
> 
> ------
> private module Detail {
>    import std.stdio;
>    import std.string;
>    import std.regex;
> }
> ....
> Detail.writefln("hi there");
> ------
> 
> This would basically be equivalent to making a separate file called 
> "Detail.d" whose contents are
> 
>    public import std.stdio;
>    public import std.string;
>    public import std.regex;
> 
> And then doing
> 
>    static import Detail;
> 
> In the original module.  Except you don't have to actually go through 
> the rigmarole of making a separate file.  *ALSO* Detail and the main 
> module would have same-module access to each others privates.
> 
> The mutual access is the big thing.  You can make separate modules now, 
> but that's not so useful for implementing a private "Detail" namespace 
> that hides a bunch of non-public functionality behind one name.  Yes, 
> you can achieve similar results with a big private {...} block but the 
> difference is that you can't give that private block a name.  By putting 
> your private stuff in one namespace, it becomes easier for readers of 
> the code to figure out what's private functionality and what's not.
> 
> The other advantage is that it makes it easier to aggregate several 
> modules under a common namespace within a module.  For instance I often 
> wish I could do something like
> 
> private module Util {
>    import std.string;
>    import my.utils;
>    import your.utils;
> }
> 
> and get at all those Util things via one Util prefix.  Yes I can do that 
> by creating another module with public imports, but I never do, because 
> its a pain, and this particular combination of Util modules is probably 
> never going to be used anywhere besides this one module.  So it doesn't 
> really make sense to create a world-visible module that's basically 
> useless aside from inside this one module.
> 
> I'm planning to throw this up as an enhancement request on Bugzilla, but 
> I thought I'd put it out here first to see what the reaction is.
> 
> --bb

It would be a nice start (and useful just on itself) if imports were to 
work on scopes other than the module scope.


-- 
Bruno Medeiros - MSc in CS/E student
http://www.prowiki.org/wiki4d/wiki.cgi?BrunoMedeiros#D