On Tue, 30 Jul 2019 at 04:00, Ethan Furman <et...@stoneleaf.us> wrote:
> If this "with...except" leads to more robust code then I think many would 
> like to use it, but not if it's confusing as that would lead to less robust 
> code.

For me, "it's for robust code" is sufficient hint that I now remember
what it does (much the same way that "it's for search loops" is the
hint I need for for...else). And when I'm trying to write robust code,
I *do* worry about exceptions in the with expression, and the fact
that I can't easily catch them. So for me, this is definitely a real
(albeit one I can usually ignore) problem.

The thing is that for most of the code I write, it's not *that*
important to be highly robust. For command line interactive utilities,
people can just fix unexpected errors and rerun the command. So
putting a lot of effort into robustness is not that important. But
then someone scripts your utility, and suddenly tracebacks are a much
bigger issue. That's why the with statement is so useful - it makes
robust exception handling low-cost to write, so my code moves a step
closer to robust-by-default. This proposal takes that a step further,
by lowering the cost of a tricky bit of boilerplate.

So I don't think it's essential, but I *do* think it would be a useful
addition to the language.

On the other hand, for...except has much less appeal, as I don't think
of for loops as blocks of code where I'd expect to be able to control
what exceptions escape (whereas in my mind that's a primary feature of
the with statement).

Paul
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