Long string interpolation lines in C#6

Question

I've found that while string interpolation is really nice when applied to my existing code base's string Format calls, given the generally preferred column limit, the string rapidly becomes too long for a single line. Especially when the expressions being interpolated are complex. With a format string you have a list of variables that you can split into multiple lines.

var str = string.Format("some text {0} more text {1}",
    obj1.property,
    obj2.property);

Does anyone have any preferred means of breaking up these lines?

I suppose you could do something like:

var str = $"some text { obj1.property }" +
  $" more text { obj2.property };

Answer 1

You can break the line into multiple lines, but I wouldn't say the syntax looks nice any more.

You need to use the $@ syntax to use an interpolated verbatim string, and you can place newlines inside the {...} parameters, like this:

string s = $@"This is all {
    10
    } going to be one long {
    DateTime.Now
    } line.";

The string above will not contain any newlines and will actually have content like this:

This is all 10 going to be one long 01.08.2015 23.49.47 line.

(note, norwegian format)

Now, having said that, I would not stop using string.Format. In my opinion some of these string interpolation expressions looks really good, but more complex ones starts to become very hard to read. Considering that unless you use FormattableString, the code will be compiled into a call to String.Format anyway, I would say keep going with String.Format where it makes sense.