Application.documentActivating Event

# Import fusion360utils folder, which includes event_utils.py.
from ...lib import fusion360utils as futil

# Global variable used to maintain a reference to all event handlers.
local_handlers = []

# "application_var" is a variable referencing an Application object.
# "application_documentActivating" is the event handler function.
futil.add_handler(application_var.documentActivating, application_documentActivating, local_handlers=local_handlers)

# Event handler for the documentActivating event.
def application_documentActivating(args: adsk.core.DocumentEventArgs):
    # Code to react to the event.
    app.log('In application_documentActivating event handler.')

# Global variable used to maintain a reference to all event handlers.
handlers = []

# "application_var" is a variable referencing an Application object.
# "MyDocumentActivatingHandler" is the name of the class that handles the event.
onDocumentActivating = MyDocumentActivatingHandler()
application_var.documentActivating.add(onDocumentActivating)
handlers.append(onDocumentActivating)

# Event handler for the documentActivating event.
class MyDocumentActivatingHandler(adsk.core.DocumentEventHandler):
    def __init__(self):
        super().__init__()
    def notify(self, args: adsk.core.DocumentEventArgs):
        # Code to react to the event.
        app.log('In MyDocumentActivatingHandler event handler.')

#include <Core/Application/Application.h>
#include <Core/Application/DocumentEvent.h>
#include <Core/Application/DocumentEventHandler.h>
#include <Core/Application/DocumentEventArgs.h>

// Event handler for the documentActivating event.
class MyDocumentActivatingEventHandler : public adsk::core::DocumentEventHandler
{
public:
    void notify(const Ptr<DocumentEventArgs>& eventArgs) override
    {
        // Code to react to the event.
        ui->messageBox("In MyDocumentActivatingEventHandler event handler.");
    }
} _documentActivating;

// "application_var" is a variable referencing an Application object.
// Connect the handler function to the event.
Ptr<DocumentEvent> documentActivatingEvent = application_var->documentActivating();
if (!documentActivatingEvent)
    return;

bool isOk = documentActivatingEvent->add(&_documentActivating);
if (!isOk)
    return;