Re: abstract sub programs overriding

["Robert I. Eachus" <rieachus@comcast.net>]

Hyman Rosen wrote:

> I don't think compilers can eliminate that Finalize call. 7.6/17 says,
> without listing any exceptions, "The target of the assignment_statement
> is then finalized." All the other permissions deal with the temporary
> anonymous object that the canonical semantics create.

Look at the last sentence, "As explained below, the implementation may 
eliminate the intermediate anonymous object..." then at 7.6(21): "For an 
aggregate or function call whose value is assigned into a target object, 
the implementation need not create a separate anonymous object if it can 
safely create the value of the aggregate or function call directly in 
the target object."

In the RM, then has a very specific meaning.  If the action before the 
then is not taken, then neither is the action following the then.  In 
this case, anything else would be silly, since finalizing the target 
after constructing the new value in it would be a disaster.

Of course, there are many cases where you can't eliminate the 
finalization, and that is covered by "...if it can safely create..." 
Certainly not finalizing an uninitialized object is safe.  (Or at least 
there is no guarantee that such objects are finalized.)

-- 

                                           Robert I. Eachus

"The only thing necessary for the triumph of evil is for good men to do 
nothing." --Edmund Burke