What are the purposes of the BaseExceptionGroup and ExceptionGroup classes in Python?

BaseExceptionGroup and ExceptionGroup are designed to group multiple exceptions and raise them as a single object.

BaseExceptionGroup:

• The base class for all exception groups.
• Abstract, not used directly.
• Contains common logic for handling exception groups.

ExceptionGroup:

• A concrete class for grouping exceptions that are subclasses of Exception.
• The most commonly used class for handling multiple errors in asynchronous code or parallel execution.
• Allows handling individual exceptions within the group using except*.

Main features:

• exceptions: Tuple of exceptions in the group.
• message: Message describing the exception group.
• subgroup(filter): Creates a new exception group containing only those exceptions from the original group that match the filter.
• split(filter): Splits the group into two: one with exceptions matching the filter, and the other with the rest. Returns a tuple (matching_group, rest_group).

Example of using except*:

# Simulating functions that raise errors
def func1():
    raise ValueError("Error in func1")

def func2():
    raise TypeError("Error in func2")

# Grouping and handling exceptions
try:
    # Simulating execution of multiple tasks
    errors = []
    try:
        func1()
    except Exception as e:
        errors.append(e)
    try:
        func2()
    except Exception as e:
        errors.append(e)

    if errors:
        raise ExceptionGroup("Multiple errors during execution", errors)

except* ValueError as ve:
    # Handling only ValueError from the group
    print(f"Caught ValueError: {ve}")
except* TypeError as te:
    # Handling only TypeError from the group
    print(f"Caught TypeError: {te}")
except ExceptionGroup as eg:
    # Handling remaining (or the entire group if no matches)
    print(f"Caught remaining exception group: {eg}")