C++ pimpl

[Robert Jacques]

On Fri, 20 Jan 2012 13:13:42 -0600, Walter Bright <newshound2 at digitalmars.com> wrote:

> On 1/20/2012 2:12 AM, Robert Caravani wrote:
>> First of all thanks for this fast answer!
>>
>>> On 1/19/2012 12:48 PM, Roberto Caravani wrote:
>>>> I think this would be a real neat and very important feature, when it
>>>> comes to shared libraries. Is there any plan to implement something
>>>> like that in the future? Do I miss something?
>>>
>>> The pimpl pros and cons are the same for C++ and D.
>>
>> Well, yes they are currently. But as D has pure reference semantics for
>> classes, it would be easier to handle the case when the size of an object is
>> not known at compile time. It basically comes down to having operator new read
>> the size from the library and having derived classes members do some offset
>> calculation. (Member initialization would have to be done by a function) Is
>> there something missing?
>>
>> Is there a flaw in my proposal? Isn't it worth the effort? What are the
>> problems?
>>
>> In Java pimpl for ABI compatibility seems not to be neccessary, according to:
>> http://java.sun.com/docs/books/jls/second_edition/html/binaryComp.doc.html
>> (It states that you can freely add and remove private fields)
>> but ok, Java is not a system programming language, they might cheat somehow.
>
> Java can recompile things on the fly.
>
>
>> Such a feature seems really cool to me, especially for library developers,
>> because they have to care less that they are implementing a dynamic library.
>> And you can easily avoid the costs if you don't need it, no rewrite necessary,
>> just a recompilation of the program. (Not even the library, if you don't care
>> about the hidden static size member and the initialization methods)
>>
>> Maybe I am completely wrong, but if so I want to know
>>
>> This is not really a feature request, as there are far more important things
>> to do at the moment. This is more a: "Is it possible?" "Would you like to have
>> it, if someone else implemented it?"
>
> What you're asking for is dynamic typing. You can achieve something equivalent
> using opDispatch and std.variant.
>

Is something like https://jshare.johnshopkins.edu/rjacque2/public_html/ what you're looking for?