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I've written a buffer class that provides a File-like interface with read, write, seek, tell, flush methods to a simple string in memory. Of course it is incomplete (e.g. I didn't write readline). It's purpose is to be filled by a background thread from some external data source, but let a user treat it like a file. I'd expect it to contain a relatively small amount of data (maybe 50K max)

Is there a better way to do this instead of writing it from scratch?

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You can use the standard Python modules StringIO or cStringIO to obtain an in-memory buffer which implements the file interface.

cStringIO is implemented in C, and will be faster, so you should use that version if possible.

If you're using Python 3 you should use the io.StringIO instead of StringIO and io.BytesIO instead of cStringIO.

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4 Comments

I think that's what I'm looking for. But are these classes thread-safe? I will have separate reader and writer threads.
Pythons GIL means that thread safety is highly unlikely to be a problem, as two threads don't execute at the same time.
That doesn't make it thread-safe. If it did, then we wouldn't need thread safety on single-core processors.
Thanks to @Sean1708 for including the Python3 notes:)
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I think you might be looking for StringIO.

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