On 2/24/2015 1:14 PM, Guido van Rossum wrote:
And I'd weigh the needs of users who know what they are doing somewhat
higher than educating newbies through error messages. While newbies are
most likely to try out open() with a string literal, in "real" programs
that is rare, and filenames are typically taken from the command line or
from some other source where the peculiarities of Python string literals
are irrelevant.
I have been thinking about proposing a new how-to: Understanding Error
Messages, with a section on tracebacks followed by an alphabetical
listing of Exceptions that gives people problems, with possible
solutions for each. The following begins my first draft.
FileNotFoundError:
Possible cause [Windows]: You used a normal string literal to create a
filename, you used '\' as the path separator, and you forgot that Python
(like most languages) treats '\' as a case-sensitive escape character.
For example: "C:\Test" is 7 chars and works as a file name, while
'C:\test' is 6 chars, one a literal tab character. The latter does not
work as a file name and will raise FileNotFoundError.
Possible solutions: 1. Use raw string literals for Windows path names
(r'C:\test'). 2 (recommended). Use '/' as the path separator
('C:/test'), just as one does on other systems. This always works when
passing file names from Python to Windows, even though it sometimes does
not work in Windows Command Prompt console.
--
Terry Jan Reedy
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