coding-mentor-agent/kb/python-course-kb-practical-python/wiki/exercises/4-11-defining-a-custom-exception.md

id, source_exercise_id, title, section, source_path, source_repo, source_commit, student_visible_solution, has_private_solution, skip

id	source_exercise_id	title	section	source_path	source_repo	source_commit	student_visible_solution	has_private_solution	skip
practical-python-4.11	4.11	Defining a custom exception	4.4 Defining Exceptions	04_Classes_objects/04_Defining_exceptions.md	https://github.com/dabeaz-course/practical-python	93dca856b41c61a0a0f85ae334116e4c125629ea	false	false	false

Exercise 4.11: Defining a custom exception

Source: Practical Python Programming, 04_Classes_objects/04_Defining_exceptions.md.

Exercise 4.11: Defining a custom exception

It is often good practice for libraries to define their own exceptions.

This makes it easier to distinguish between Python exceptions raised in response to common programming errors versus exceptions intentionally raised by a library to a signal a specific usage problem.

Modify the create_formatter() function from the last exercise so that it raises a custom FormatError exception when the user provides a bad format name.

For example:

>>> from tableformat import create_formatter
>>> formatter = create_formatter('xls')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "tableformat.py", line 71, in create_formatter
    raise FormatError('Unknown table format %s' % name)
FormatError: Unknown table format xls
>>>

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关联来源

• summaries/04_Defining_exceptions