errr

Elegantly create detailed exceptions in Python.

Detailed exceptions

>>> import errr
>>> class MyException(errr.DetailedException, list_detailts=True, details=["cause", "type"]):
...  pass
...
>>> example = MyException("The backend server crashed", "backend", "crash")
>>> raise example
__main__.MyException: The backend server crashed

Details:
 ˪cause: backend
 ˪type: crash
>>> example.details
{'cause': 'backend', 'type': 'crash'}
>>> example.cause
'backend'

Semantic exceptions

You can also rapidly create large semantic trees of exceptions using the make_tree function, listing exceptions as keyword arguments using the errr.exception factory method. The make_tree method executes these recursive factories to produce your exceptions. Nesting these factory methods will make the resultant exceptions inherit from eachother. All of the produced exceptions are then flat injected into the given module dictionary (typically) this should be globals() but you can inject into other modules using sys.modules["name"].__dict__.

from errr import make_tree, exception as _e

make_tree(
  # Pass the module dictionary as first argument
  globals(),
  # List your nested exceptions
  RootException=_e(
    ChildException=_e(),
    Child2Exception=_e()
  ),
  SecondRootException=_e(
    # List details as positional arguments
    "detail1", "detail2",
    # And continue with child exceptions as keyword arguments
    AnotherChildException=_e()
  )
)

print(RootException)
# <class '__main__.RootException'>
print(ChildException)
# <class '__main__.ChildException'>
print(ChildException.__bases__)
# (<class '__main__.RootException'>,)

Exception wrapping

You can catch and reraise exceptions as a new type of exception with the wrap function:

import errr

class LibraryError(errr.DetailedException, details=["library"]):
  pass

for name, library in libraries.items():
  try:
    library.load()
  except Exception as e:
    errr.wrap(LibraryError, e, name, prepend="When trying to load %library% it reported:\n")
# Traceback
#   ...
# __main__.LibraryError: When trying to load myLibrary it reported:
# Module 'missing' not found.