python regex include end-of-line char in capture group or not?

Question

When doing a search within a line that includes the end of the line should one include the $ into the capture group or not?

Example included:

x=re.search("\S+(bla\S+bla$)",line)

Example excluded:

x=re.search("\S+(bla\S+bla)$",line)

Are there significant advantages / risks of one over the other?

Thanks.

Answer 1

The $ ending anchor is zero-width, meaning that even if you do capture it, it won't contribute anything to the capture group. So, I might actually consider the first version to be an anti-pattern, and would therefore always use the second version:

x = re.search("\S+(bla\S+bla)$", line)

In both cases, the underlying pattern is the same, so I would expect the regex engine to take the same steps, and have the same performance.