"Steven D'Aprano" <st...@pearwood.info> wrote
Wrapping an atomic block of code, so long as it actually *can* be
treated as atomic (including backing out any changes if it fails),
is a good use of try...except.
That's exactly what I meant by atomic. A (smallish) group of
instructions
that must be treated as a group, if any one fails the whole block
fails
and must be backed out or aborted.
Provided the entire try block needs to be treated as a single
operation (in which case, why isn't it a function?)
The point about the function is good and the try/except can live
within the function.
a single operation. That is, the individual sub-tasks should have no
side-effects, or they must be backed out off on failure.
Absolutely. That is the key criterion.
It has been said that error handling is ten times harder than
handling the rest of your code.
Yep, and usually takes up about ten times as much code.
I once analyzed a largish project - about 1.5 million lines of C++.
Only ~250k lines were actual funcionality, the rest were split between
GUI (before GUI Builders etc) and error handling (and some logging
for our IT department's benefit). I can't recall the split between GUI
and errors but it was scary to see how little was real functonal
code...
( This didn't include any SQL or script files but it was before the
days
of stored procedures so most of the SQL was probably ermbedded
in the C++ anyway).
HTH,
--
Alan Gauld
Author of the Learn to Program web site
http://www.alan-g.me.uk/
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