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