On 27.06.2017 13:41, Nick Coghlan wrote:
The shallow exception notion breaks a fairly fundamental refactoring
principle in Python: you should be able to replace an arbitrary
expression with a subfunction or subgenerator that produces the same
result without any of the surrounding code being able to tell the
difference.
I would agree with you here but this "refactoring principle in Python"
doesn't work for control flow.
Just look at "return", "break", "continue" etc. Exceptions are another
way of handling control flow. So, this doesn't apply here IMO.
By contrast, Steven's exception_guard recipe just takes the existing
"raise X from Y" feature, and makes it available as a context manager
and function decorator.
I don't see how this helps differentiating shallow and nested exceptions
such as:
try:
with exception_guard(ImportError):
import myspeciallib
except RuntimeError: # catches shallow and nested ones
import fallbacks.MySpecialLib as myspeciallib
Regards,
Sven
PS: this has nothing to do with cyclic imports. It can be a
misconfiguration of the system which fails nested imports. In those
cases, we fallback silently.
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