Return to Revisions

I believe a better idea is to use

raise NewException("Explain why") from CatchedException

pattern. In particular, considering Python 3 and the example given by @BrenBarn I use following

def failure():
    raise ValueError("Real error")

try:
    failure()
except ValueError as ex:
    raise TypeError("Apology error") from ex

which yields

--------------------------------------------------------------------------- ValueError                                Traceback (most recent call last) ~\AppData\Local\Temp\ipykernel_15716\1525308893.py in <module>
      4 try:
----> 5     failure()
      6 except ValueError as ex:

~\AppData\Local\Temp\ipykernel_15716\1525308893.py in failure()
      1 def failure():
----> 2     raise ValueError("Real error")
      3 

ValueError: Real error

The above exception was the direct cause of the following exception:

TypeError                                 Traceback (most recent call last) ~\AppData\Local\Temp\ipykernel_15716\1525308893.py in <module>
      5     failure()
      6 except ValueError as ex:
----> 7     raise TypeError("Apology error") from ex

TypeError: Apology error