On Tue, Oct 13, 2020 at 6:18 AM Steven D'Aprano <steve@pearwood.info> wrote:
I don't think that a two line class (perhaps a couple of extra
lines if you give it a docstring) justifies the name "boilerplate":

    class MySpecialException(Exception):
        pass

I think that in 22 years of using Python, I have never written an exception that took more than these two lines of code.

Heck, I even have my memory jogged of string exceptions reading this.  When did those go away fully, 1.5.2? 2.1?

I DID in the discussion, immediately think of making an exception a dataclass, as someone else replied with.  I guess if you want cargo in your exception, that's a pretty good way to do it.  But really the ONLY thing I ever want in an exception is an inheritance tree.  An exception feels like a really unnatural way to pass around data (that said, there are a few exceptions written by other libraries where some attribute or another is useful in my except blocks.  Perhaps I should consider that, beyond inspecting the traceback when needed.

If you really want a snazzy highly-parameterized exception, write it yourself as a class factory.  I won't particularly like the antipattern, but it's available now.

if some_bad_thing:
    raise ExceptionMaker("BadStuffErrror", details, plus, more_details)

Implementation of 'ExceptionMaker' left to readers.  But it's possible to write once.