Compile time executable calling?

[Timothee Cour]

On Mon, Jul 15, 2013 at 9:10 PM, Andrei Alexandrescu <
SeeWebsiteForEmail at erdani.org> wrote:

> On 7/15/13 6:26 AM, Don wrote:
>
>> On Friday, 12 July 2013 at 20:42:50 UTC, Tofu Ninja wrote:
>>
>>> So I had an idea recently, wouldn't it be cool to have the ability to
>>> call an executable at compile time and capture its output. Something
>>> like the string imports but instead of opening and reading a text
>>> file, it run an executable, waits for it to finish, and grabs its output.
>>>
>>> It would get really cool if you could pass this executable some args
>>> and then mix in its out put into your own code. It could be used
>>> similarly to how CTFE are used but with out the overhead of trying to
>>> compile that function and what not and with out the limitations on
>>> what it can do.
>>>
>>> I could imagine all sorts of things that would be possible with this
>>> that is currently not.
>>>
>>> Not sure if this is something that could be implemented easily, but
>>> seems like something that could be done and something that would be
>>> really cool.
>>>
>>
>> I personally think it's a *horrible* idea. It's one of those things
>> which looks good in small cases but doesn't scale.
>>
>
> I think the right direction here is to factor compiler parts as a library.
> Then user code may insert external artifacts (notably REPL) on its own.
>
>
CTFE exec would still be needed (see yet another use case in EMAIL:"Proof
of concept: automatically import C header files"), but having a
compiler-as-a-library would make implementation easier and more
customizable, eg by redirecting certain symbols  such as 'CTFE exec' to a
given delegate.

myfile.d:
import std.process;
void main(){enum HOME=exec("echo $HOME", Redirect.all);}

driver.d:
import std.compiler;
void exec_dg(){...}
void main(){"myfile.d".readText.compile(&exec_dg);}
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