ImportC can now automatically run the preprocessor

[max haughton]

On Monday, 16 May 2022 at 03:12:47 UTC, Walter Bright wrote:
> But I still don't understand - why mixin this stuff? Why would 
> someone want to type C code into a D source file?

dpp and dstep are not always able to divine the meaning of a 
given macro, so having an escape hatch is either necessary or the 
most direct way of doing certain things.

If you use them you can see that they're just looking for 
relatively simple patterns, not magic. You can approximate magic 
a little by looking at how a macro is used within a source file 
(if you're lucky), but extracting this info programmatically 
would use a lot of niche infrastructure and thinking that is 
probably beyond reachh.

ImportC does not (currently) emit a D equivalent to a header 
file, which means that documenting what it actually does for some 
non-trivial preprocessor metaprogramming uglyvomityuck is going 
to be irritating.

You have a C API, dstep might turn that into a template, which 
might be initially confusing but you can just grep (or use an 
IDE) for the symbol (or lack thereof if it couldn't do it). With 
ImportC this is now much murkier for obvious reasons (although 
I'll note that adding a palatable header-output mode is something 
I've played around with and honestly wouldn't be particularly 
hard as long as we kept a little bit more info around in the 
compiler).

So you're in a hurry and you can't seem to get a macro working? 
mixinC the bit you need. It's either that or doing it in your 
head anyway.