Question

I’m writing some code that needs functionality that is almost satisfied by the ReadBytes method in the bufio package. Specifically, that method reads from a Reader until it encounters a particular byte. I need something that reads till it encounters one out of couple of bytes (space, newline and tab mainly).

I looked at the source for the library and I know what to do if I have access to the internal buffer used by bufio structs. Is there any way I could “monkey patch” the package and add another method or two to it? Or another way to get the functionality I need?

Answer 1

Something along this approach (caution: untested code):

type reader struct{
        *bufio.Reader // 'reader' inherits all bufio.Reader methods
}

func newReader(rd io.Reader) reader {
        return reader{bufio.NewReader(rd)}
}

// Override bufio.Reader.ReadBytes
func (r reader) ReadBytes(delim byte) (line []byte, err error) {
        // here goes the monkey patch
}

// Or

// Add a new method to bufio.Reader
func (r reader) ReadBytesEx(delims []byte) (line []byte, err error) {
        // here goes the new code
}

EDIT: I should have noted that this doesn’t help to access the original package internals (non exported entities). Thanks Abhay for pointing that out in your comment.