Note that the description for system errors may be used by h5py

[takluyver]

Following discussion on #34, we decided that this could simply be a comment in the source code. The string format here has been stable for 11 years (since a443284), so hopefully there's no major pressure to change it.

We're just about to release h5py 3.0, so we'll look into getting the errno from the string after that.

[byrnHDF]

I am not disagreeing with the idea, just the content of the message.
I think the specific use of one project, h5py, is the main issue. It should be more general, something like:
/* Other projects may rely on the description format to get the errno and any changes should be considered as an API change */

[takluyver]

That makes sense; I've updated the comment.

[qkoziol]

Nice!

[takluyver]

Thanks! I am planning to only rely on the errno part. Specifically, we're likely to match it with a regex like errno = (\d+).