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Comment by quickben | Hacker News Reader

I don't see this making it into the standard.

1. Interface = abstract class, already present.

2. Reflection, rtti is sparsely used because c++ is primarily used for speed and large teams.

3. Reserved words prefixed by $, etc. Well, outside of a preprocessor directives, that will be a first , if it ever happens.

By the look of the thing, the author wants c++ to be more like c#. But c++ isn't restricting on patterns, we create them. Unlike c# there is no language defined way for dependency injection, interfaces etc. Well we can argue that, but c++ is more flexible on pattern creation, and this proposal wants to put two patterns inside the standard. I just don't see it happening.

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1. It's about abstracting what "classes" are, since the built-in "class" metaclass is trying to be one-size-fits-all. Yes, an interface is an abstract class, and if you could do things like make your own "interface" metaclass, then you can "create more patterns," in your words.

2. This is compile-time reflection, which is how a metaclass generates code, so there shouldn't be much of a run-time speed consideration. I think the comparison with C# isn't quite right; if anything, the author wants C++ to be more like Lisp, Smalltalk, or even Python, which all have at least some semblance of a meta-object protocol (and code-writing code, in the case of Lisp).

1. Classes itself can be improved, but at this point, will they date breaking compatibility? Maybe from that perspective this will be given a shot.

2. More code at compile time would work. Pythinizing may work. Lisp is quite different.

Indeed. I think this is one of the best things about the proposal: it offers a way out of the current hardcoded behaviours. At the moment we barely even think about whether or not they're correct, because they're obviously too hard to opt out of.

If anything, the proposal corners people into more hardcoded behaviours.

Don't see why, you don't have to use the keywords given, and in the future existing keywords could be deprecated.

1. $interface is just one example. Look at the $value example and defining an operator == which automatically works for all members: that does not yet exist 2. Some (or all? not sure..) of the reflection capabilities this brings are compile-time so no runtime speed penalty 3. There's a first for everything :]

That being said, I'm also not sure it if will make it to the standard but for different reasons; mainly that it's a pretty huge change and will make C++ even more mature/difficult/one language to rule them all/easier to rant on/...

indeed, there is one thing i don't understand: why $class and not metaclass...

It can be $meta-class::class :)

Keep in mind simple=elegant is not in everybody's eyes.

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