Overload Resolution and Optional Arguments in C# 4
- by Dale McCoy
I am working with some code that has seven overloads of a function TraceWrite:
void TraceWrite(string Application, LogLevelENUM LogLevel, string Message, string Data = "");
void TraceWrite(string Application, LogLevelENUM LogLevel, string Message, bool LogToFileOnly, string Data = "");
void TraceWrite(string Application, LogLevelENUM LogLevel, string Message, string PieceID, string Data = "");
void TraceWrite(string Application, LogLevelENUM LogLevel, string Message, LogWindowCommandENUM LogWindowCommand, string Data = "");
void TraceWrite(string Application, LogLevelENUM LogLevel, string Message, bool UserMessage, int UserMessagePercent, string Data = "");
void TraceWrite(string Application, LogLevelENUM LogLevel, string Message, string PieceID, LogWindowCommandENUM LogWindowCommand, string Data = "");
void TraceWrite(string Application, LogLevelENUM LogLevel, string Message, LogWindowCommandENUM LogWindowCommand, bool UserMessage, int UserMessagePercent, string Data = "");
(All public static, namespacing noise elided above and throughout.)
So, with that background:
1) Elsewhere, I call TraceWrite with four arguments: string, LogLevelENUM, string, bool, and I get the following errors:
error CS1502: The best overloaded method match for 'TraceWrite(string, LogLevelENUM, string, string)' has some invalid arguments
error CS1503: Argument '4': cannot convert from 'bool' to 'string'
Why doesn't this call resolve to the second overload? (TraceWrite(string, LogLevelENUM, string, bool, string = ""))
2) If I were to call TraceWrite with string, LogLevelENUM, string, string, which overload would be called? The first or the third? And why?
