Proposal: FileIO.save keyword argument syntax (FileIO.kwsave ?) about fileio.jl

[johnnychen94]

I like this idea, I think we can deprecate the single-positional-argument method in favor of a manually written one data->save(f, data). But this takes time to proceed and I don't know how others feel about it.

In the meantime, adding a non-exported symbol kwsave seems okay to me. When the deprecation finishes, we can deprecate kwsave in favor of save.

[timholy]

I recognize it's useful functionality, and we should keep it. But it's undocumented behavior of FileIO.save and it doesn't really fit with any Julia standard elsewhere (neither the "omit an IO object and fill in a default" nor the "first argument is a function which you can define via a do block"). I think we could call this something new, maybe writer, to hint that it returns a function that writes data? Or might savestreaming already solve that problem in a more conventional way?

[davidanthoff]

I think we can deprecate the single-positional-argument method

This is very heavily used in queryverse. The entire file IO story revolves around this pattern, so I would be very, very opposed to this :)