lawrence_danna marked 2 inline comments as done.
lawrence_danna added inline comments.
================
Comment at:
lldb/source/Plugins/ScriptInterpreter/Python/PythonDataObjects.h:235-245
PythonObject &operator=(const PythonObject &other) {
Reset(PyRefType::Borrowed, other.get());
return *this;
}
- void Reset(PythonObject &&other) {
+ PythonObject &operator=(PythonObject &&other) {
Reset();
----------------
labath wrote:
> lawrence_danna wrote:
> > labath wrote:
> > > lawrence_danna wrote:
> > > > labath wrote:
> > > > > You can consider simplifying this further down to a
> > > > > "universal"/"sink" `operator=(PythonObject other)`. Since the object
> > > > > is really just a pointer, the extra object being created won't hurt
> > > > > (in fact, the removal of `&`-indirection might make things faster).
> > > > wouldn't that result in an extra retain and release every time a
> > > > PythonObject was copied instead of referenced or moved?
> > > No, it shouldn't, because the temporary PythonObject will be
> > > move-constructed (== no refcount traffic), if the operator= is called
> > > with an xvalue (if the rhs was not an xvalue, then you wouldn't end up
> > > calling the `&&` overload anyway). Then you can move the temporary object
> > > into *this, and avoid refcount traffic again.
> > >
> > > So, there is an additional PythonObject created, but it's
> > > move-constructed if possible, which should be efficient, if I understand
> > > these classes correctly. This is the recommended practice (at least by
> > > some) when you don't want to squeeze every last nanosecond of
> > > performance..
> > How do you move the temporary object into *this, if you only have
> > `operator=(PythonObject other)` to assign with?
> In case that wasn't clear, the idea is to replace two operator= overloads
> with a single universal one taking a temporary. The advantage of that is less
> opportunities to implement move/copy incorrectly. The cost is one temporary
> move-constructed object more.
so does that amount to just deleting the copy-assign, and keeping the
move-assign how it is?
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D69080/new/
https://reviews.llvm.org/D69080
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