What are your favorite extension methods for C#? (codeplex.com/extensionoverflow)

Answer 1

My conversion extensions which allow you to do:

int i = myString.To();

Here it is, as posted on TheSoftwareJedi.com

public static T To(this IConvertible obj)
{
  return (T)Convert.ChangeType(obj, typeof(T));
}

public static T ToOrDefault
             (this IConvertible obj)
{
    try
    {
        return To(obj);
    }
    catch
    {
        return default(T);
    }
}

public static bool ToOrDefault
                    (this IConvertible obj,
                     out T newObj)
{
    try
    {
        newObj = To(obj); 
        return true;
    }
    catch
    {
        newObj = default(T); 
        return false;
    }
}

public static T ToOrOther
                       (this IConvertible obj,
                       T other)
{
  try
  {
      return Toobj);
  }
  catch
  {
      return other;
  }
}

public static bool ToOrOther
                         (this IConvertible obj,
                         out T newObj,
                         T other)
{
    try
    {
        newObj = To(obj);
        return true;
    }
    catch
    {
        newObj = other;
        return false;
    }
}

public static T ToOrNull
                      (this IConvertible obj)
                      where T : class
{
    try
    {
        return To(obj);
    }
    catch
    {
        return null;
    }
}

public static bool ToOrNull
                  (this IConvertible obj,
                  out T newObj)
                  where T : class
{
    try
    {
        newObj = To(obj);
        return true;
    }
    catch
    {
        newObj = null;
        return false;
    }
}

You can ask for default (calls blank constructor or "0" for numerics) on failure, specify a "default" value (I call it "other"), or ask for null (where T : class). I've also provided both silent exception models, and a typical TryParse model that returns a bool indicating the action taken, and an out param holds the new value. So our code can do things like this

int i = myString.To();
string a = myInt.ToOrDefault();
//note type inference
DateTime d = myString.ToOrOther(DateTime.MAX_VALUE);
double d;
//note type inference
bool didItGiveDefault = myString.ToOrDefault(out d);
string s = myDateTime.ToOrNull();

I couldn't get Nullable types to roll into the whole thing very cleanly. I tried for about 20 minutes before I threw in the towel.