Exception.args holds the arguments passed to the exception. You could add type checking with dataclass, or you can just access Exception.args or sys.exc_info().args: ```python class Exception2(Exception): pass try: raise Exception2('error str', dict(a='1', b=2)) except Exception2 as e: print(('args', e.args)) assert e.args[0] == 'error str' assert e.args[1] == dict(a='1', b=2) import sys type_, value, traceback = sys.exc_info() assert value.args[0] == 'error str' assert value.args[1] == dict(a='1', b=2) # ('args', ('error str', {'a': '1', 'b': 2})) ``` On Tue, Oct 13, 2020 at 12:56 PM David Mertz <mertz@gnosis.cx> wrote:
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.
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