[Tutor] Potential problem with Game Over 2.0 problem in "Python Programming for the Absolute Beginner, 3rd Ed."

[Dave Angel]

On 02/17/2015 02:12 PM, boB Stepp wrote:

See 
https://docs.python.org/3.4/reference/lexical_analysis.html#string-and-bytes-literals
>
> At this point in the text he is not talking about raw literal strings.
> I examined the author's source and he has obviously inserted at least
> one space between each use of a backslash at the end of a line and the
> EOL terminating characters.

Then he's teaching you wrong. Backslash followed by space is not a valid 
escape sequence, and to do it at the end of line is particularly odious. 
  I wouldn't even suggest it in real code, never mind in something 
that's published on paper.

The docs admit that the invalid escape sequences behave differently than 
C, in that the backslash is retained.  I think it should be a syntax 
error to have an invalid sequence.

If the backslash immediately precedes the newline, then the two 
characters both get eaten, and the two lines are combined into one. 
That can be useful if you want to define a string that's too long to fit 
in your source file.

I would never intentionally make any trailing whitespace in source code 
be significant.  And years ago I used an editor that routinely deleted 
any such invisible characters.  From the rest of your message, it looks 
like IDLE may have that behavior.


> He did not do this with the "Game" portion
> of the code, which did not make any use of "\" . When the file is run
> everything behaves as desired. But if, as my son did, you leave no
> spaces between the last backslash and the EOL termination characters,
> then the problem behavior occurs.



-- 
DaveA