How to imitate string.Format() in my own method?

Question

I have an object with a custom WriteLine(string) method. Something like this:

public void WriteLine(string text) {     this.StringList.Add(text); } 

What is the easiest way to duplicate the functionality of string.Format() with this method? For example: What I currently often find myself doing is this:

myObj.WriteLine(string.Format("Hello, {0}", name)); 

If you create a new Console application their version of a WriteLine() method does exactly what I would prefer to do:

Console.WriteLine("Hello, {0}", name); 

They eliminate the need to call string.Format(). Is it easy to make your method accept this somehow? Or am I going to have to create a thousand method overloads? Something like this:

public void WriteLine() { ... }  public void WriteLine(string text) { ... }  public void WriteLine(string text, object arg0) { ... }  public void WriteLine(string text, object arg0, object arg1) { ... }  public void WriteLine(string text, object arg0, object arg1, object arg2) {     this.StringList.Add(string.Format(text, arg0, arg1, arg2)); }  // etc etc etc 

Is that the only logical way to do this? Any suggestions are welcomed :)

Answer 1

You need to copy the method signature from string.format.

public void WriteLine(string text,params object[] args) {   this.StringList.Add(string.Format(text,args)); } 

As suggested by ChaosPandion you can also include overloads to prevent array creation

public void WriteLine(string text) {   this.StringList.Add(text); }  public void WriteLine(string text,object arg0) {   this.StringList.Add(string.Format(text, arg0)); }  public void WriteLine(string text,object arg0, object arg1) {   this.StringList.Add(string.Format(text, arg0, arg1)); }  public void WriteLine(string text,object arg0, object arg1, object arg2) {   this.StringList.Add(string.Format(text, arg0, arg1, arg2)); } 

I wouldn't go past arg2 as string.format doesn't so the benefit disappears.

Answer 2

There is one edge case you might want to take pains to avoid. The following code will write the string {0} to the console

Console.WriteLine("{0}"); 

However, you use one of the implementations of WriteLine suggested by others in this answer, those implementations will throw an exception:

WriteLine("{0}"); //throws exception 

The easiest fix is either to have two overloads of WriteLine or to modify the suggested code slightly to handle the edge case:

public void WriteLine(string text,params object[] args) {   var message=args.Length==0 ? text : string.Format(text, args);   this.StringList.Add(message); }