Is it possible to use multiple interpolation characters for verbatim strings

[fgheysels]

I have a verbatim string that represents a JSON string, like this:

string s = @"{""property"": ""somevalue""}";

Now, I'd like to change "somevalue" to the contents of a variable using string interpolation, so I thought I'd be able to do this:

string foo = "something else";
string s = @$$"{""property"": ""{{foo}}""}";

or even this:

string foo = "something else";
string s = @$$"""{"property": "{{foo}}"}""";

However, the compiler issues this error:

CS9008: Sequence of '@' character is not allowed. A verbatim string or identifier can only have one '@' character and a raw string cannot have any.

If I switch the verbatim indicator and the string-interpolation indicator, the same error remains.

Is it not possible to combine both in this case ?
I have specified the 'Preview' LangVersion in my csproj file.

[HaloFour]

You don't use the @ with raw strings:

string foo = "something else";
string s = $$"""{"property": "{{foo}}"}""";

IIRC the ability to double-up interpolation indicators is not supported with verbatim strings, only raw strings.

[FaustVX]

You have raw string literals: #4304
sharplab.io

Ok, @HaloFour answered just before :)