Stroustrup on the new features of C + + 11

Reprinted from http://www.stroustrup.com/C++11FAQ.html

For personal reference only, for collection

Control of Defaults:move and copyby default, A-class has 5 operations:

• Copy Assignment
• Copy constructor
• Move Assignment
• Move constructor
• destructor

If You declare any of those to must consider all and explicitly define or default the ones you want. Think of copying, moving, and destruction as closely related operations, rather than individual operations that you can FR eely mix and match-you can specify arbitrary combinations, but only a few combinations make sense semantically.

If any move, copy, or destructor are explicitly specified (declared, defined, =default, or =delete) by the user, no move is Generated by default. If any move, copy, or destructor are explicitly specified (declared, defined, =default, or =delete) by the user, any undecl Ared copy operations is generated by default, but it is deprecated and so don ' t rely on that. For example:

Disallow copying

This implicitly also disallows moving of X1S. Copy initialization is allowed, but deprecated.

This implicitly also disallows moving of X2S. Copy initialization is allowed, but deprecated.

Disallow Moving

This implicitly also disallows copying of X3S.

Disallow Destruction

This implicitly also disallows moving of X4S. Copying is allowed, but deprecated.

I strongly recommend so if you declare one of the these five function, you explicitly declare all. For example:

user-defined destructor:no implicit copy or move   transfer ownershiptransfer Ownership  /c5>no copy handle& operator= (const handle&) = delete;  ...

See Also

• The C + + Draft section???
• [n2326==07-0186] Lawrence crowl:defaulted and Deleted Functions.
• [n3174=100164] B. Stroustrup:to move or not to move. An analysis of problems related to generated copy and move operations. Approved.

Stroustrup on the new features of C + + 11