[Python-ideas] Possible PEP regarding the use of the continue keyword in try/except blocks

[Robert Collins]

On Sun., 6 Jan. 2019, 13:39 Simon <simon.bordeyne at gmail.com wrote:

>
> I was writing some python code earlier, and I noticed that in a code that
> looks somwhat like this one :
>
>     try:
>         i = int("string")
>         print("continued on")
>         j = int(9.0)
>     except ValueError as e:
>         print(e)
>
> >>> "invalid literal for int() with base 10: 'string'"
>
> this code will handle the exception, but the code in the try block will
> not continue.
>
> I propose to be able to use the continue keyword to continue the execution
> of the try block even when an error is handled. The above could then be
> changed to :
>

In terms of implementation, I think continue would be problematic

while true:
    try:
        x = foo()
        return x
    except:
        continue

is already valid code. You'd need some way of disambiguating, either a
keyword or parameter to continue. Both of which would require a very big
benefit for us to do, given the ecosystem impact that such things have.


>     try:
>         i = int("string")
>         print("continued on")
>         j = int(9.0)
>     except ValueError as e:
>         print(e)
>         continue
>
> >>> "invalid literal for int() with base 10: 'string'"
> >>> "continued on"
>

Exception handling is not internally line orientated,  so this proposed
resume functionality doesn't map exactly. But if the following in the same
way as what you envision:

def handle(f, *args):
    try:
        return f(*args)
    except ValueError as e:
        print(e)

i = handle( int, "string")
handle(print, "continued on")
j = handle(int, 9.0)

Then I have to say I'm not sure what you are trying to solve. Is it the
verbosity? Is it the flow control?
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