Module Clarification

[Jonathan Marler via Digitalmars-d-learn]

On Tuesday, 27 September 2016 at 13:48:39 UTC, Steven 
Schveighoffer wrote:
> On 9/22/16 4:16 PM, Jonathan Marler wrote:
>> On Thursday, 22 September 2016 at 20:09:41 UTC, Steven 
>> Schveighoffer wrote:
>>>
>>> Before package.d support, you could not do any importing of 
>>> packages.
>>> You could only import modules. package.d was how the compiler 
>>> allowed
>>> importing packages.
>>>
>>> I don't know that there is a fundamental difference between
>>> foo/package.d and foo.d, but this is just the solution that 
>>> was
>>> chosen. Is it a mistake? I don't think so, it's just a 
>>> preference.
>>>
>>> Prior to this, it was common to put "package" imports into an 
>>> "all.d"
>>> file:
>>>
>>> foo/all.d // import fooPart1.d fooPart2.d
>>> foo/fooPart1.d
>>>
>>
>> Ok, do you know why is this not allowed?
>
> I'm sure if you search the forums, you can find discussions of 
> this. Walter probably had a reason. I'm not sure if the reason 
> is valid anymore now that package.d is supported.
>
> -Steve

foo.d
foo/bar.d

I would think the reason for not supporting this is you wouldn't 
want something to be a "module" and a "package" at the same time, 
but introduction of the "package.d" semantics has broken that 
rule.

 From what I can see, it seems like the concept of "packages" 
doesn't have any useful meaning anymore.  Before adding 
"package.d" support, a "package" was a directory/node you could 
find modules underneath, but now that it can also be a module 
itself, saying something is a "package" doesn't really have any 
meaning. Take the following 2 cases:

Case 1: foo.d
Case 2: foo/package.d

In case 1, foo is a "module", and in case 2, foo is a "package".  
The problem is that foo can behave EXACTLY THE SAME in both 
cases.  foo could contain typical module code, or publicly import 
other modules like a typical "package.d" file, in both cases.  
Saying that foo is a "package" doesn't tell you anything about 
how "foo" behaves.  The "package" concept seems pretty 
meaningless now.