> Lie. In my world, this is commonly referred to as an "option". It seems a bit unfair to call Chen a liar on this point since the very same paragraph you quot

> Lie. In my world, this is commonly referred to as an "option". It seems a bit unfair to call Chen a liar on this point since the very same paragraph you quoted from ends like this: "A change in the regular expression syntax would require a new switch to opt into the new behavior." (I do think it's pretty weird that he portrays this as a major problem. I suppose the point is that if you care about backwards compatibility your options aren't "crappy old RE syntax" and "nice new RE syntax", they're "crappy old RE syntax" and "crappy old RE syntax as default, and nice new RE syntax with an option" and that's not so appealing because (1) now maybe your program needs two regexp engines in it and (2) even a trivial inconvenience like remembering to add the option is something of a nuisance.)