I have often encountered an error such as “cannot convert from ‘method group’ to ‘string'” in cases like:
var list = new List<string>(); // ... snip list.Add(someObject.ToString);
of course there was a typo in the last line because I forgot the invocation parentheses after
ToString. The correct form would be:
var list = new List<string>(); // ... snip list.Add(someObject.ToString()); // <- notice the parentheses
A method group is the name for a set of methods (that might be just one) – i.e. in theory the
ToString method may have multiple overloads (plus any extension methods):
ToString(string format), etc – hence
ToString by itself is a “method group”.
It can usually convert a method group to a (typed) delegate by using overload resolution – but not to a string etc; it doesn’t make sense.
Once you add parentheses, again; overload resolution kicks in and you have unambiguously identified a method call.