DIP81: Writing files at compile time

[JDemler via Digitalmars-d]

On Wednesday, 12 August 2015 at 23:27:16 UTC, Tofu Ninja wrote:
> On Wednesday, 12 August 2015 at 18:37:40 UTC, JDemler wrote:
>> Triggered by the original forum thread I wrote a DIP to 
>> further explain the idea of the writing files at compile time 
>> feature and its implications.
>>
>> http://wiki.dlang.org/DIP81
>>
>> Please discuss!
>
> The benefits of this I see are debugging, actually having the 
> generated files makes it much simpler to see what is going 
> wrong. Otherwise the utility of this can be achieved with 
> string mixins.
>
> A simple alternative to this would be a flag to the compiler to 
> expand mixins and output the new files. This would also be 
> great for tooling, an IDE could use this and allow you to 
> expand a mixin in place to see what it looks like. And 
> currently all the auto complete engines I have seen for D don't 
> handle mixins very well. Expanding them would make 
> autocompletion a simpler job.

While this might work for very simple and basic mixins, with the 
combination of TMP and compile time reflection this becomes not 
only impractical but also impossible.

Think again about the vibe.d example:
There is one mixin handeling all the template-type combinations.
How would such a mixin be expanded? The resulting code differs 
from template to template and from type to type.