What is StringIO in python used for in reality?

Question

I am not a pro and I have been scratching my head over understanding what exactly StringIO is used for. I have been looking around the internet for some examples. However, almos

Answer 1

Couple of things I personally have used it for:

1. Whole-file caching. I have a script that reads PDFs and does validation of various things about them. The PDF library I'm using takes an open file in its document constructor. I originally just opened the PDF I was interested in reading, however when I changed it to read the entire file at once into memory then pass a StringIO object to the PDF library, the running time of my script was cut in half.

2. Deferred printing. Same script prints a header before every PDF it reads. However, I can specify on the command line whether to ignore certain tests that are in its configuration file, or to only include certain ones. If I ignore all tests for a given PDF I don't want the header printed, but I won't know how many tests I ran until I'm done running the tests (the tests can be defined dynamically as well). So I capture the header into a StringIO object by changing sys.stdout to point to it, and each time I run a test I check to see whether that object has anything in it. If so, I print it then and reset it to empty. Voila, only PDFs that have tests have headers printed.