@disable

[Leandro Lucarella]

Clemens, el 15 de enero a las 04:40 me escribiste:
> Andrei Alexandrescu Wrote:
> 
> > Clemens wrote:
> > > Andrei Alexandrescu Wrote:
> > > 
> > >> The main idea is to allow creation of noncopyable types by marking 
> > >> this(this) as @disable.
> > > 
> > > I must be missing something, but isn't this usually done by making the copy constructor private?
> > 
> > Well one issue is that in D private has module granularity, which means 
> > that inside a given module you could still create objects. That has the 
> > advantage of obviating the need for "friend", but disables the private 
> > constructor idiom.
> > 
> > Andrei
> 
> I thought about that, but it seemed to me that the D philosophy is that
> modules can be trusted to "do the right thing" internally. Then again,
> I can see how, due to its implicit nature, invoking a copy constructor
> "accidentally" may be easier than invoking a private method, leading to
> subtle bugs.

Exactly, that seems like a contradiction: we are confident that the module
author know what he is doing giving him rights to access private data, but
we are not so sure about certain functions...

I know it could be useful to have more granularity, but maybe we need
a new visibility attribute, like "module" (making "private" really
private, and "module" what "private" actually does). Changing "private"
meaning is probably a bad idea though, maybe private can be left as is and
add a "delete" visibility attribute (which would have the same effect than
@disable, but is more close to the current way to do things).

class X {

	private this();

	delete this(X);

}

It would be even more familiar to people coming from C++0x (C++1x! =P)

-- 
Leandro Lucarella (AKA luca)                     http://llucax.com.ar/
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