Using percent signs with SafeConfigParser

Peter Otten __peter__ at web.de
Sat Apr 11 21:06:52 CEST 2009


Márcio Faustino wrote:

> Does the SafeConfigParser class correctly detects lone percent signs?
> For example, shouldn't the string "100%%" be accepted as a valid
> value? Executing the code below should only print one error, instead
> it prints 2. (I've tested this with version 2.6.1 on Windows XP.)
> 
> It seems the "_badpercent_re" regular expression (an attribute of
> SafeConfigParser, with value "%[^%]|%$") is flawed:
> - The first alternative "%[^%]" fails with the string "%%_", because
> it matches "%_".
> - The second alternative "%$" fails with the string "%%", because it
> matches "%".

I think you are right. Please file a bug report .

> The correct regular expression is "(?<!%)%(?!%)", which passes the
> previous tests.

IMO this doesn't fix the problem because 

(1) it allows "%%%" which is also incorrect
(2) _interpvar_re has already butchered values like "%%(alpha)s" to "%"

Peter



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