On Friday, 20 December 2013 at 22:40:16 UTC, Timon Gehr wrote:
http://wiki.dlang.org/DIP49
Improved points from version 1:
- Swap meanings of 'this(this) inout' and 'this(this) const'
- Inout postblit now covers all cheap (== not rebind
indirections)
copies between same qualifiers
Kenji Hara
What about just mentioning the qualifiers of source and target
of the copy explicitly?
this(this){ ... } // mutable source, mutable target
this(immutable this){ ... } // immutable source mutable target
this(const this)immutable{ ... } // const source, immutable
target
this(const this)const{ ... } // const source, const target
// ...
this(inout this)inout{ ... } // source and target have the same
qualifier
// ...
this(this)inout{ ... } // mutable source, arbitrary target
// ...
this(const this)inout{ ... } // const source, arbitrary target
Whenever source and target are (potentially) incompatible, the
postblit ensures that all fields with incompatible types in
source and target are reinitialized.
Only unique expressions convert to 'inout' anyway, hence the
last signature above would correspond to unique postblit in the
current proposal.
This would be more explicit, strictly more expressive and
require less special casing in the compiler implementation.
I agree, it will be the most powerful solution. And we should use
the same rules for constructor behavior.
Also, we have strange rules in DIP 53:
If mutable constructor is defined, if immutable constructor is
not defined, it will be used for const object construction.
If immutable constructor is defined, if mutable constructor is
not defined, it will be used for const object construction.
What happens if we have both mutable and immutable constructors?
