add output offset for readpartial/read_nonblock/etc
Specifying a destination offset will allow allocating less garbage strings to improve performance when reading partial data off a pipe or socket. For example: tmp = "".b buf = "".b case rv = io.read_nonblock(8192, tmp, exception: false) when String buf << tmp break if parsing_done?(buf) else return rv end while true Can be written as: buf = "".b case rv = io.read_nonblock(8192, buf, exception: false, off_out: buf.size) when String break if parsing_done?(buf) else return rv end while true For reference, here is the relevant part from "perldoc -f sysread" sysread FILEHANDLE,SCALAR,LENGTH,OFFSET sysread FILEHANDLE,SCALAR,LENGTH -snip- An OFFSET may be specified to place the read data at some place in the string other than the beginning. A negative OFFSET specifies placement at that many characters counting backwards from the end of the string. A positive OFFSET greater than the length of SCALAR results in the string being padded to the required size with "\0" bytes before the result of the read is appended. -snip- Maybe we can shortcut by allowing "off_out: :end" to avoid redundant words and potentially using the wrong variable: io.read_nonblock(8192, buf, exception: false, off_out: :end) I'm not sure when I'll have time to work on this feature. Lately I've been working in Perl again and rediscovered this API subtlety.