writeto(clobber=True) writes a message to stderr about pyfits

[embray]

I'm somewhat inclined to agree, but clearly somebody wanted it. If it's a problem you can always disable it: http://docs.astropy.org/en/stable/warnings.html

[ycopin]

Indeed I could disable all astropy's UserWarning's, but at the price of all other rightful warnings.

Is it true that somebody explicitly wanted it, or just used warning.warn as a standard way to print out confirmation information?

[embray]

Yes, that's pretty normal. It's useful for user applications, but for libraries you can just disable them entirely or filter as needed. You can disable specific warnings with a filter: http://docs.python.org/2/library/warnings.html#warning-filter

That said, I'll ask around about it. I found when it was originally added, some nine years ago: 67ac28d#diff-8b4ff7071b289a061e4717473affeb6b
Originally it was just a print statement to stdout so at least that's been fixed ;) I agree that if you've already asked to overwrite existing files maybe you don't need to know about it. Though perhaps one could make a case that it's there so that programs that use PyFITS can use the "clobber" functionality, but the users of those programs don't necessarily know that it will overwrite existing files, so it's informing end-users of that fact...

[ycopin]

I can indeed encapsulate all calls to writeto in the proper warning management, thanks for the tip (yet not very appealing...). Maybe an alternative would be to define an explicit IOwarning which could be specifically filtered when needed.