On quarta-feira, 6 de junho de 2012 21.56.16, lars.kn...@nokia.com wrote: > >https://codereview.qt-project.org/26981-Optimisedeletion > > I might be wrong (getting tired), but I think this reintroduces the > problem with forward declared pointers that the first patch fixes.
It's a different solution.
The Qt 4 solution for this was to return false from a virtual function (the
default implementation), which would require the caller to perform the
deletion. The code was like this:
if (!d->destroy())
delete value;
This function was called from deref(), which meant that where a reference
could be dropped also required a full definition of the class.
The new optimisation does not introduce "delete value" into the reference-
dropping code path. That is still:
d->destroy()
which does:
void destroy() { destroyer(this); }
(destroyer is a function pointer)
The optimisation simply changes what the pointed function does. Wiithout it,
it will call another stored function pointer. With it, it will call delete
directly.
--
Thiago Macieira - thiago.macieira (AT) intel.com
Software Architect - Intel Open Source Technology Center
Intel Sweden AB - Registration Number: 556189-6027
Knarrarnäsgatan 15, 164 40 Kista, Stockholm, Sweden
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