Automated source translation of C++ to D

[Xavier Bigand via Digitalmars-d]

Le 22/08/2014 09:48, Daniel Murphy a écrit :
> "Joakim"  wrote in message news:ynfwlptfuzfutksbnslc at forum.dlang.org...
>
>> Yes, I'm aware of ddmd.  You've mentioned many times that it only
>> works because dmd is written using a very unC++-like style, to the
>> point where github's source analyzer claims that dmd is written in
>> 66.7% C, 28.4% D (presumably the tests right now), 4.4% C++, and 0.5%
>> other. :)
>
> The style dmd is written in makes it a lot easier, but it would still be
> possible with other styles.  As others have said the github numbers have
> nothing to do with the style of the code, only the naming of the files.
>
>> Given tools like libclang, how hard do you think it'd be to translate
>> most of actual C++ to D?  If writing such a tool would mean that
>> C++->D translation is the path of least effort for D users who want to
>> integrate with C++, maybe that's the approach that should be taken
>> instead.
>
> A tool that can translate an arbitrary C++ program to D is not going to
> happen.
>
> A tool that can translate a specific C++ program to D is not
> particularly difficult to produce, as I've done with dmd.  eg multiple
> inheritance cannot be generally mapped to D code.  But in many
> applications, the use of multiple inheritance _can_ be mapped because it
> corresponds to classes + interfaces.  This type of application-specific
> knowledge can significantly reduce the complexity.
>
> DDMD actually has a major additional complication that most translations
> would not have - it is only a partial translation (glue layer stays in
> C++) and therefore needs abi stability across the boundary.  I initially
> did a non-abi-stable translation of only the frontend, and it was rather
> easy in comparison.
>
> So no, you can't magically upgrade a project from C++ to D.  But it can
> be done, and is not prohibitively difficult someone experienced with C++
> and D.

As many told it including Walter it seems impossible to be able to 
convert arbitrary C++ code to D, but having a tool that is well 
documented on what it can convert without issue will certainly be enough 
interesting.

My point is, if some part of your C++ can't be converted you certainly 
can refactor it to fit in something supported by the conversion tool.
Here the point is the tool must not be able to do imperfect conversion, 
it better to exit in error when something isn't well supported.

As Andrei told, there is certainly ways to do a configurable tool, to 
help it to convert some parts.

Even if a such tool can't convert any C++ code, it might help to 
interface C++ with D, by converting the main part (every day modified 
code) of a C++ software. In this sense I am more interested by 
converting the C++ I write than those of third party libraries. Maybe 
just as Facebook?

The other question is what will be the result of the generated binary in 
term of performances?