DIP11

[Nick Sabalausky]

"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.

> And there is no parsing of the output data,

Parsing the .deps file is extremely simple. RDMD does it with one regex. 
Personally, I think even that is overkill.

Better yet, with a switch to make DMD incorporate RDMD's --build-only 
functionality, there is *still* no parsing of output data.

So all in all, there is *nothing* that DIP11 does that can't be done 
*better* by other (more typical) means.