On Sat, Jun 08, 2013 at 08:38:56PM +0200, Matthieu Moy wrote: > Célestin Matte <celestin.matte@xxxxxxxxxx> writes: > > > In Perl, '\n' is not a newline, but instead a literal backslash followed by an > > "n". As the output of "rev-list --first-parent" is line-oriented, what we want > > here is a newline. > > This is right, but the code actually worked the way it was. I'm not > sure, but my understanding is that '\n' is the string "backslash > followed by n", but interpreted as a regexp, it is a newline. Yes, the relevant doc (from "perldoc -f split") is: The pattern "/PATTERN/" may be replaced with an expression to specify patterns that vary at runtime. (To do runtime compilation only once, use "/$variable/o".) So it is treating "\n" as an expression and compiling the regex each time through (though I think modern perl may be smart enough to realize it is a constant expression and compile the regex only once). You would get the same behavior with this: split $arg, $data; if $arg contained '\n'. Of course, you _also_ get the same thing if you use a literal newline (either "\n" or if $arg contained a literal newline), because they function the same in a regex. In other words, it does not matter which you use because perl's interpolation of "\n" and the regex expansion of "\n" are identical: t hey both mean a newline. A more subtle example that shows what is going on is this: split '.', $data; If you feed that "foo.bar.baz", it does not split it into three words; each character is a delimiter, because the dot is compiled to a regex. > The new code looks better than the old one, but the log message may be > improved. Agreed. I think the best explanation is something like: Perl's split function takes a regex pattern argument. You can also feed it an expression, which is then compiled into a regex at runtime. It therefore works to pass your pattern via single quotes, but it is much less obvious to a reader that the argument is meant to be a regex, not a static string. Using the traditional slash-delimiters makes this easier to read. -Peff -- To unsubscribe from this list: send the line "unsubscribe git" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html