Re: proposal: PL/Pythonu - function ereport

After I unzip the patch it doesn't apply.
patch says:
patch: **** Only garbage was found in the patch input.

It's a combined diff, the git-diff manual says this about it:
Chunk header format is modified to prevent people from accidentally
feeding it to patch -p1. Combined diff format was created for review
of merge commit changes, and was not meant for apply.

Thanks for doing the test changes. It definitely shows the change is
big. The tests at least were heavily relying on both the str
conversion and on passing more than one argument. Sad face. 

You're going to hate me but seeing this I changed my mind about 5,
requiring all those extra str calls is too much change in behaviour. I
was going to propose passing everything through str (so message,
detail, hint but also schema, table) but thinking about it some more,
I think I have something better.

Python 3 has keyword only arguments. It occurs to me they're exactly
for "optional extra stuff" like detail, hint etc.
Python 2 doesn't have that notion but you can kind of fake it since
you get an args tuple and a kwargs dictionary.

What about keeping the same behaviour for multiple positional
arguments (single one -> make it str, multiple -> use str of the args
tuple) and requiring users to pass detail, hint only as keyword
arguments? Code wise it would only mean adding PyObject* kw to
PLy_output and adding some code to extract detail, hint etc. from kw.
This would also allow getting rid of the GUC since backward
compatibility is fully preserved.

Again, sorry for all the back and forth but it still feels like we
haven't nailed the design to something satisfactory. All the tests you
needed to change are a hint towards that.