Why doesn't ignorecase flag (re.I) work in re.sub() [duplicate]

Question

From pydoc:

re.sub = sub(pattern, repl, string, count=0, flags=0)
Return the string obtained by replacing the leftmost non-overlapping occurrences of the pattern in string by the replacement repl. repl can be either a string or a callable; if a string, backslash escapes in it are processed. If it is a callable, it's passed the match object and must return a replacement string to be used.

example code:

import re print re.sub('class', 'function', 'Class object', re.I) 

No replacement is made unless I change pattern to 'Class'.

Documentation doesn't mention anything about this limitation, so I assume I may be doing something wrong.

What's the case here?

Answer 1

Seems to me that you should be doing:

import re print(re.sub('class', 'function', 'Class object', flags=re.I)) 

Without this, the re.I argument is passed to the count argument.

Answer 2

The flags argument is the fifth one - you're passing the value of re.I as the count argument (an easy mistake to make).