package.d behavior

[Leandro Motta Barros]

Hello!

About a month ago I asked in D.learn about the expected behavior of the new
package.d feature [1]. I got a cuple of responses, but not really answers.
Today I noticed a second post [2] with similar but still unanswered
questions. So it seemed like a good idea to bring the discussion to the
main forum.

Basically, I seems that the root of the issues we are facing is the way
fully-qualified names work when using package.d (I have added some examples
below showing what I mean).

We also felt that the feature is under-documented (DIP37 and the changelog
seem to be the only places where the feature is discussed, and some
important details are missing.) I was actually about to fill bug a report
about the behavior, but I ended up not doing so because I couldn't find out
what the expected behavior is.

So, any feedback and clarifications are welcome!

Thanks for the attention, and keep up the great work :-)

LMB

[1]
http://forum.dlang.org/thread/CANY+vSMzLJ5ehKGW8cE1KkoMOm7x3roKmVgMjyCqZrwD9aLO9w@mail.gmail.com
[2] http://forum.dlang.org/thread/eeaslvjwenkygwszqznc@forum.dlang.org


-----------------------

EXAMPLE 1: Trying to simply replace the old "all.d" idiom with package.d
doesn't work out-of-the-box:

Originally, I had something like this:

 // mylib/util.d:
 module mylib.util;
 class Foo { }

 // mylib/all.d:
 module mylib.all;
 public import mylib.util;

 // main.d:
 import mylib.all;
 void main()
 {
    auto f = new mylib.util.Foo;
 }

And this used to work. Now, I added a new file:

 // package.d
 module mylib;
 public import mylib.util;

And changed the 'import' in the main one:

 // main.d
 import mylib;

 void main()
 {
    auto f = new mylib.util.Foo;
 }

Now, the compiler complains:

 main.d(5): Error: undefined identifier 'util'
 main.d(5): Error: mylib.util.Foo is used as a type

[Using mylib.Foo instead of mylib.util.Foo works -- which makes sense when
thnking about the use case of using package.d to split a large package into
smaller ones. ]


---------------------

EXAMPLE 2: Inconsistency with fully-qualified names

// mylib/util.d
module mylib.util;
class Foo { }

// mylib/package.d
module mylib;
public import mylib.util;

// main.d
import std.stdio;
import mylib;

void main()
{
   auto f = new mylib.Foo;
   writefln("%s", f.classinfo.name);
}

This prints 'mylib.util.Foo'. So far so good, that's the name I originally
expected.

Then I try to instantiate a 'Foo' using this very fully-qualified name the
compiler told me:

   auto f = new mylib.util.Foo;

And DMD doesn't like it anymore:

main.d(6): Error: undefined identifier 'util'
main.d(6): Error: mylib.util.Foo is used as a type

[This looks very much like a bug for me. The name given by
classinfo.nameshould be usable to instantiate a class, shouldn't it? ]
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