How to use Workbook.Application in the xlwings API way

The Application member of a Workbook object in xlwings provides a gateway to the overarching Excel application instance. This is a powerful property because it allows you to control Excel-wide settings, access other open workbooks, and interact with application-level features directly from a specific workbook context. Essentially, Workbook.app (or the full property Workbook.application) returns the main App object to which the workbook belongs, enabling you to scale your automation from a single file to the entire Excel environment.

Functionality:
The primary function is to retrieve the parent App object. Through this App object, you can:

• Control Excel application settings (e.g., DisplayAlerts, ScreenUpdating, Calculation).
• Access all open workbooks via the App.books collection.
• Create new workbooks or open existing ones at the application level.
• Quit the Excel application entirely.

Syntax:
The access is straightforward as it is a property.

app_instance = my_workbook.app
# or equivalently
app_instance = my_workbook.application

• my_workbook: A xlwings Book object (the Python representation of an Excel Workbook).
• app_instance: The returned xlwings App object. This object has its own set of properties and methods.

Code Examples:

1. Accessing Application Properties from a Workbook:
   This example shows how to disable screen updating and alerts via the App object retrieved from a specific workbook, perform an operation, and then restore the settings.

import xlwings as xw

# Connect to an existing workbook
wb = xw.Book("Report.xlsx")

# Get the parent Excel Application
excel_app = wb.app

# Configure application-wide settings
excel_app.screen_updating = False
excel_app.display_alerts = False

# Perform operations (e.g., add a new sheet)
new_sheet = wb.sheets.add("NewData")

# Restore settings
excel_app.screen_updating = True
excel_app.display_alerts = True

2. Listing All Open Workbooks:
   Using the App object from one workbook to interact with others.

import xlwings as xw

wb1 = xw.Book("Financials.xlsx")
app = wb1.app

print("Workbooks currently open in this Excel instance:")
for open_wb in app.books:
    print(f" - {open_wb.name}")

3. Creating a New Workbook in the Same Instance:
   Ensures a new workbook is created in the same Excel application window as your current workbook.

import xlwings as xw

source_wb = xw.Book("SourceData.xlsx")
app = source_wb.app

# Create a new workbook in the same Excel instance
new_wb = app.books.add()
new_wb.sheets[0].range("A1").value = "Report Generated from " + source_wb.name