DIP11

[Andrei Alexandrescu]

On 8/11/11 1:09 PM, Nick Sabalausky wrote:
> "Steven Schveighoffer"<schveiguy at yahoo.com>  wrote in message
> news:op.vz166yaieav7ka at localhost.localdomain...
>> On Thu, 11 Aug 2011 12:24:48 -0400, Andrew Wiley
>> <wiley.andrew.j at gmail.com>  wrote:
>>
>>> On Thu, Aug 11, 2011 at 5:52 AM, Steven Schveighoffer
>>> <schveiguy at yahoo.com>wrote:
>>>> I think the benefit of this approach over a build tool which wraps the
>>>> compiler is, the compiler already has the information needed for
>>>> dependencies, etc.  To a certain extent, the wrapping build tool has to
>>>> re-implement some of the compiler pieces.
>>>>
>>>
>>> This last bit doesn't really come into play here because you can already
>>> ask
>>> the compiler to output all that information. and easily use it in a
>>> separate
>>> program. That much is already done.
>>
>> Yes, but then you have to restart the compiler to figure out what's next.
>> Let's say a source file needs a.d, and a.d needs b.d, and both a.d and b.d
>> are on the network. You potentially need to run the compiler 3 times just
>> to make sure you have all the files, then run it a fourth time to compile.
>>
>
> That's *only* true if you go along with DIP11's misguided file-oriented
> approach. With a real package manager, none of that is needed. Your app just
> says "I need packages X, Y and Z."
> And X, Y and Z do the same for their requirements. This is all trivial
> metadata. Emphasis on *trivial*. So, before DMD is ever invoked at all,
> before one line of the source is ever even read, the package manager has
> make sure that *everything* is *already* right there. No need to go off on
> some goofy half-cocked "compile/download/complile/download" dance.
>
> So DMD *never* needs to be invoked more than twice. Once to get the deps,
> once to compile. Better yet, if DMD gets the
> switch --compile-everything-dammit-not-just-the-explicit-files-from-the-command-line,
> then DMD never needs to be invoked more than *once*: Once to figure out the
> deps *while* being intelligent enough to actually compile all of them.

It's difficult to get all dependencies when not all sources have been 
yet downloaded.

Andrei