coding-mentor-agent/kb/python-course-kb-practical-python/wiki/exercises/3-17-from-filenames-to-file-like-objects.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-3.17	3.17	From filenames to file-like objects	3.6 Design Discussion	03_Program_organization/06_Design_discussion.md	https://github.com/dabeaz-course/practical-python	93dca856b41c61a0a0f85ae334116e4c125629ea	false	false	false

Exercise 3.17: From filenames to file-like objects

Source: Practical Python Programming, 03_Program_organization/06_Design_discussion.md.

Exercise 3.17: From filenames to file-like objects

You've now created a file fileparse.py that contained a function parse_csv(). The function worked like this:

>>> import fileparse
>>> portfolio = fileparse.parse_csv('Data/portfolio.csv', types=[str,int,float])
>>>

Right now, the function expects to be passed a filename. However, you can make the code more flexible. Modify the function so that it works with any file-like/iterable object. For example:

>>> import fileparse
>>> import gzip
>>> with gzip.open('Data/portfolio.csv.gz', 'rt') as file:
...      port = fileparse.parse_csv(file, types=[str,int,float])
...
>>> lines = ['name,shares,price', 'AA,100,34.23', 'IBM,50,91.1', 'HPE,75,45.1']
>>> port = fileparse.parse_csv(lines, types=[str,int,float])
>>>

In this new code, what happens if you pass a filename as before?

>>> port = fileparse.parse_csv('Data/portfolio.csv', types=[str,int,float])
>>> port
... look at output (it should be crazy) ...
>>>

Yes, you'll need to be careful. Could you add a safety check to avoid this?

关联来源

• summaries/06_Design_discussion