[Python-Dev] PEP 344: Explicit vs. Implicit Chaining

[Ka-Ping Yee]

Guido van Rossum wrote:
> Do we really need both __context__ and __cause__?

Well, it depends whose needs we're trying to meet.

If we want to satisfy those who have been asking for chaining
of unexpected secondary exceptions, then we have to provide that
on some attribute.

If we also want to provide the facility that Java and C# provide
with initCause/InnerException, then we need a separate attribute
devoted to explicit chaining.  The Java and C# documentation is
clear that the cause/inner exception is to be set only on an
exception that is "caused" or a "direct result" of the primary
exception, which i've taken as a sign that this is an important
distinction.

I wanted to give a shot at making both camps happy.

If the two were unified, we'd still be better off than we are
now, but we should be aware that we would not be providing the
functionality that Java and C# provide.


-- ?!ng