How to use Application.CustomListCount in the xlwings API way

The CustomListCount member of the Application object in Excel refers to the total number of custom lists available in the Excel application. Custom lists are user-defined sequences (e.g., a list of department names, product categories, or regional offices) that can be used for autofill and sorting operations. This property is read-only and returns a Long integer representing the count. In xlwings, you can access this property to programmatically determine how many custom lists are currently defined, which is useful for automating tasks that depend on these lists, such as data validation or dynamic range naming based on list entries.

Syntax in xlwings:
The property is accessed through the Application object. In xlwings, you typically start by instantiating an app or using the active app. The syntax is straightforward:

app.custom_list_count

Here, app is an instance of the xlwings App class, representing the Excel application. The property takes no parameters and directly returns an integer value. For example, if you have defined three custom lists in Excel (e.g., “Q1, Q2, Q3, Q4”, “East, West, North, South”, and “Low, Medium, High”), calling app.custom_list_count will return 3.

Example Usage:
Below is a practical xlwings code example that demonstrates how to use the CustomListCount property. This example checks the number of custom lists and prints a message based on the count. It also shows how to iterate through custom lists if needed (though note that accessing individual list details requires other properties like CustomList, which is not covered here as per the focus on CustomListCount).

import xlwings as xw

def check_custom_lists():
# Connect to the active Excel instance or start a new one
app = xw.apps.active # Use the currently active Excel application

# Get the count of custom lists
count = app.custom_list_count

# Output the result
print(f"Number of custom lists available: {count}")

# Example logic based on the count
if count == 0:
    print("No custom lists are defined. Consider creating some for autofill or sorting tasks.")
elif count <= 5:
    print("A moderate number of custom lists are available. Suitable for basic automation.")
else:
    print("Many custom lists are available. Ideal for complex data processing workflows.")

# Optional: Close the app if it was started by xlwings (uncomment if needed)
# app.quit()

# Run the function
if __name__ == "__main__":
check_custom_lists()