How compiler handles string interpolation

问题

I am using string interpolation for a method attribute like -

const string User = "SomeUser";
const string Admin = "Admin";
.
.
.
[Authorize(Roles = $"{User},{Admin}")]
public IHttpActionResult Get()

But Visual Studio gives an error -

An attribute argument must be a constant expression, typeof expression or array creation expression of an attribute parameter type

When I try "+" for string concatenation it works

[Authorize(Roles = User + "," + Admin)]
public IHttpActionResult Get()

Even if I replace "," with ',' it gives the same error.

I wonder how the compiler is handling string interpolation?

回答1:

string interpolation is converted to string.Format which isn't a compile time constant as it requires kindly review this question for more information

来源：https://stackoverflow.com/questions/54740725/how-compiler-handles-string-interpolation