* The former is only needed inside tp_init of a new object. Instead when
we want to pass in and own a pointer, we use SWIG_POINTER_OWN.
* This also removes the need to pass 'self' all the way down in
ConvertToPy which tidies up a lot of code.
* In future we could handle async exceptions by storing the exception
information in a std::function derived object (instead of the separate
ExceptionHandling that lives on the stack) and query it out in a new
WaitForInvoke function maybe. Right now we just print the exception
to the output log and abort the callback.
* Even if we don't have pyside2 to treat qwidgets as full objects and
access their methods and data, we still need to be able to pass around
the QWidget* as an opaque pointer to be able to use the API properly.
* This change falls back to just using SWIG's default opaque pointer
wrapping and unwrapping when pyside2 isn't available.
* Added a couple of utility macros to help with the conversion. lit() is
paired with tr() for untranslated text.
* QFormatStr is more explicitly for non-textual formatting strings.
* Both are just #define'd to QStringLiteral()
* If it's called every write then it risks spamming the system with
signals and locking the UI thread with constant writes. Checking and
flushing output every 100ms is sufficient.
* We need to keep a PythonContext (and its globals Dict) around while
we still have some pending callbacks happening. So now the external
code creates a PythonContext and then releases it when it's done, but
the context will hang around until the global redirector object is
destructed, which is responsible for deleting the context.
* The global redirector is deleted when a refcounting cycle is detected
and the dict is unreachable, which only happens after the context is
released.
* Any time a callback is passed to something and converted to a
std::function we add a reference on the global redirector to keep it
alive. When the callback has finished executing we remove the ref.
* This way, any pending callbacks that have been called but not finished
or converted (queued) and not called yet asynchronously will keep the
context object alive to be able to output, handle exceptions, etc.
* Additionally we need to detect when we're being called asynchronously
and handle exceptions separately instead of trying to propagate up the
call chain, because there might not be any more python code up the
chain (e.g. the render manager calling a python callback).
* Using a separate dict for globals/locals for each interpreter means we
still get separation of variables and no persistence where we don't
want it, but removing sub-interpreters means pyside can work as it
uses the PyGILState_ APIs which do not support sub-interpreters.
* We import everything up front then duplicate the __main__ each time we
create a new context so we keep the __main__ pristine and muck up an
individual copy.
* Because sys is now shared, the output redirectors that overwrite
sys.stdout and sys.stderr have a NULL context, and instead they look
up a specific global which contains the actual context pointer.
baldurk