Proposal: this.d

[Tomas Lindquist Olsen]

Kirk McDonald wrote:

> I brought this up in the "Modules vs Packages" thread, where it was
> received positively. I think it deserves its own thread.
> 
> Suppose you have a package, called pkg:
> 
> pkg/
>    foo.d
>    bar.d
>    baz.d
> 
> It is useful to have a central import-point for the package. By
> convention, this is often called "pkg.all" or "pkg.pkg". It might look
> like this:
> 
> // pkg/all.d
> module pkg.all;
> 
> public import foo : a, b;
> public import bar : c, d;
> //----
> 
> Then the user of your package would "import pkg.all;" and get your
> package's public API.
> 
> This is a common enough operation that I propose adding language support
> for it.
> 
> When a user says "import pkg;" (where pkg is a package), it should
> actually import a special module called "pkg/this.d". The name "this",
> being a keyword, cannot be used as a regular module name, and so there
> is no chance of it interfering with existing packages. It also evokes
> existing D syntax.
> 
> Our above example would look like this:
> 
> pkg/
>    this.d
>    foo.d
>    bar.d
>    baz.d
> 
> // pkg/this.d
> module pkg;
> 
> public import foo : a, b;
> public import bar : c, d;
> //----
> 
> Saying "import pkg;" refers to this module.
> 
> The module declaration requires some explanation. Using either "module
> pkg;" or "module pkg.this;" might work, but either option is a little
> inconsistent. The important point here is that the name the module is
> imported as is different than its filename. (This is why the feature
> requires compiler support.)
> 
> Using "module pkg;" is to be preferred, since it is the name the module
> is imported as. It is not difficult to, given "import pkg;", determine
> that "pkg" is a directory, and look for a this.d inside it. Nor is it
> difficult to do the reverse: Given a file named "this.d", determine that
> it is the import point of a package.
> 
> There is one detail to go over. Suppose we say "import pkg;". Should we
> now be able to say "pkg.baz", even though the name "baz" is not
> publically imported inside of pkg/this.d? I would say no. In this
> respect, the this.d should act no differently than any other module.
> This is, if nothing else, the simplest behavior.
> 

I would like to see:
import package x;

The package keyword is probably one of the least used keywords in D (I guess
because it's buggy) and this way there is no doubt what is happening.

My $0.02