yeah, typically you would get error if you use variable length lookbehinds a few do support it (for ex: Python's 3rd party regex module) and sometimes you coul

yeah, typically you would get error if you use variable length lookbehinds a few do support it (for ex: Python's 3rd party regex module) and sometimes you could workaround with \K (similar to \zs in vim) [1] And there are other frustrating differences between implementations, for example \g definition is very different between Ruby and Python, character set operations are not found everywhere, etc. Plus, BRE/ERE versions found in command line tools do not even support features like non-greedy and lookaround [1] https://stackoverflow.com/questions/11640447/variable-length-lookbehind-assertion-alternatives-for-regular-expressions https://stackoverflow.com/questions/11640447/variable-length...