Yarp: String nightmare in ConnectionReader/Writer

[randaz81]

The following methods are problematic:

• yarp::os::ConnectionReader::expectText(const char terminatingChar = '\n')
• yarp::os::ConnectionWriter::appendString(const char* str,const char terminatingChar = '\n' )
• yarp::os::ConnectionWriter::appendRawString(const std::string& s)

Currently, the only proved way to receive a string is as: size+blob of bytes, e.g.

    int string_size = connection.expectInt32();
    this->map_id.resize(string_size);
    connection.expectBlock(const_cast<char*>(this->map_id.data()), string_size);

[drdanz]

After some investigation, I agree that this part is a nightmare. I'm planning to:

• Replace ConnectionWriter::appendString with appendText (appendString will be deprecated)
• Replace ConnectionWriter::appendRawString with appendString (different signature) (appendRawString deprecated)
• Add ConnectionReader::expectString
• Cleanup string serialization all around in YARP code. (This includes changing code generated by thift, but since I have a huge refactor on the way, I'm going to change this later).

The goal is to have either appendText -> expectText or appendString -> expectString

Since there are pure interfaces involved, this is going to be a breaking change, but I searched these methods using github search, and they seem to be used only inside YARP.

[Nicogene]

Fixed by #1972