Why exception from os.path.exists()?

[Steven D'Aprano]

On Thu, 31 May 2018 17:43:28 +0000, Grant Edwards wrote:

> Except on the platform in quetion filenames _don't_ contain an embedded
> \0.  What was passed was _not_ a path/filename.

"/wibble/rubbish/nobodyexpectsthespanishinquistion" is not a pathname on 
my system either, and os.path.exists() returns False for that. As it is 
supposed to.

I'd be willing to bet that:

import secrets  # Python 3.6+
s = "/" + secrets.token_hex(1024) + "/spam"

is not a pathname on any computer in the world. (If it is even legal.) 
And yet os.path.exists(s) returns False.

The maximum number of file components under POSIX is (I believe) 256. And 
yet:

py> os.path.exists("/a"*1000000)
False

"/a" by one million cannot possibly be a path under POSIX.


> the thread will continue for months and generate hundreds of followup.

Only because some people insist on exercising their right to be wrong.


-- 
Steven D'Aprano
"Ever since I learned about confirmation bias, I've been seeing
it everywhere." -- Jon Ronson