Irregular last line in a text file, was Re: Regular expressions

[Ian Kelly]

On Tue, Nov 3, 2015 at 9:56 AM, Tim Chase <python.list at tim.thechases.com> wrote:
> On 2015-11-03 16:35, Peter Otten wrote:
>> I wish there were a way to prohibit such files. Maybe a special
>> value
>>
>> with open(..., newline="normalize") f:
>>     assert all(line.endswith("\n") for line in f)
>>
>> to ensure that all lines end with "\n"?
>
> Or even more valuable to me:
>
>   with open(..., newline="strip") as f:
>     assert all(not line.endswith(("\n", "\r")) for line in f)
>
> because I have countless loops that look something like
>
>   with open(...) as f:
>     for line in f:
>       line = line.rstrip('\r\n')
>       process(line)

What would happen if you read a file opened like this without
iterating over lines?