labath 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();
----------------
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.
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D69080/new/
https://reviews.llvm.org/D69080
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