Proof of Concept: Binding to and extending C++ objects via a metric fuckton of templates

[Don]

downs wrote:
> I've just committed a module to tools (tools.cpp, http://dsource.org/projects/scrapple/Trunk/tools/tools/cpp.d ) that should enable linking and using any C++ library with D programs without creating a C wrapper for it.
> 
> The code has been tested with a simple multiple-inheritance sample: http://paste.dprogramming.com/dpv8hpjp
> 
> The D code to bind to this is http://paste.dprogramming.com/dphlv1ot . It requires a symlink to the tools folder in its directory.
> 
> Caveats:
> 
>  - D1
>  - Only works on g++4's "newapi" layout and mangling (but should be reasonably portable).

At http://www.agner.org/optimize/, you can find a document 
(calling_conventions.pdf) which gives full details of the C++ name 
mangling schemes for various compilers.

> Writing this also gave us what I believe to be a fair contender to Most Horrifying Statement of D Ever Written:
> 
>   fndefs ~= `mixin("extern(C) `~t~` "~`~mname~`~"`~fnparams~`; ");`~'\n'~
>       `mixin("`~fn~`("~refToParamList("Params!(typeof(&"~`~mname~`~"))", isRef!(typeof(mixin("&"~`~mname~`))))~") {
>       return "~`~mname~`~"("~refToValueList(isRef!(typeof(mixin("&"~`~mname~`))))~");
>     }
>   "); `;

Ugh, that's unreadable.

I found that with a little function called string enquote(string s), 
which changes s into "s",  this kind of stuff looks much less terrible.
In particular you get rid of the nasty mix of ` and ".

fndefs ~= "mixin(" ~ enquote("extern(C)" ~ t ~ " ")
                    ~ "~" ~ mname
                    ~ "~" ~ enquote(fnparams ~ ";")
              ~ ");"
         ~ "mixin(" ~ ....

// etc