Advanced Optional Parameters (c#) [duplicate]

Question

The below code would be quite cool if it worked. However, I can't get it to compile, so I'm assuming this isn't going to work in any form?

public void foo(char[] bar = new char[]{'a'})
{
}

The next-best option is to just do

public void foo(char[] bar = null)
{
   if (bar==null)
      bar = new {'a'};
}

Answer 1

No it's not possible. The default value needs to be a compile-time constant. The default value will be inserted into the caller, not the callee. Your code would be a problem if the caller has no access to the methods used to create your default value.

But you can use simple overloads:

public void foo(char[] bar)
{
}

public void foo()
{
  foo(new char[]{'a'});
}