How do I make the return type of a method generic

Question

Is there a way to make this method generic so I can return a string  bool  int  or double   Right now  it s returning a string  but if it s able find  true  or  false  as the configuration value  I d like to return a bool for example       public static string ConfigSetting string settingName                   return ConfigurationManager AppSettings settingName

User · Accepted Answer

You need to make it a generic method  like this   public static T ConfigSetting lt T gt  string settingName          return    code to convert the setting to T           But the caller will have to specify the type they expect  You could then potentially use Convert ChangeType  assuming that all the relevant types are supported   public static T ConfigSetting lt T gt  string settingName          object value   ConfigurationManager AppSettings settingName       return  T  Convert ChangeType value  typeof T        I m not entirely convinced that all this is a good idea  mind you

User · Answer

You have to convert the type of your return value of the method to the Generic type which you pass to the method during calling       public static T values lt T gt                  Random random   new Random            int number   random Next 1  4           return  T Convert ChangeType number  typeof T            You need pass a type that is type casteable for the value you return through that method     If you would want to return a value which is not type casteable to the generic type you pass  you might have to alter the code or make sure you pass a type that is casteable for the return value of method  So  this approach is not reccomended

User · Answer

private static T   prepareArray lt T gt  T   arrayToCopy  T value                Array Copy arrayToCopy  1  arrayToCopy  0  arrayToCopy Length - 1           arrayToCopy arrayToCopy Length - 1    value          return  T   arrayToCopy          I was performing this throughout my code and wanted a way to put it into a method   I wanted to share this here because I didn t have to use the Convert ChangeType for my return value   This may not be a best practice but it worked for me   This method takes in an array of generic type and a value to add to the end of the array   The array is then copied with the first value stripped and the value taken into the method is added to the end of the array   The last thing is that I return the generic array

User · Answer

There are many ways of doing this listed by priority  specific to the OP s problem    Option 1  Straight approach - Create multiple functions for each type you expect rather than having one generic function   public static bool ConfigSettingInt string settingName           return Convert ToBoolean ConfigurationManager AppSettings settingName       Option 2  When you don t want to use fancy methods of conversion - Cast the value to object and then to generic type   public static T ConfigSetting lt T gt  string settingName           return  T  object ConfigurationManager AppSettings settingName       Note - This will throw an error if the cast is not valid your case   I would not recommend doing this if you are not sure about the type casting  rather go for option 3  Option 3  Generic with type safety - Create a generic function to handle type conversion   public static T ConvertValue lt T U gt  U value  where U   IConvertible       return  T Convert ChangeType value  typeof T         Note - T is the expected type  note the where constraint here type of U must be IConvertible to save us from the errors

User · Answer

Please try below code    public T  GetParsedOrDefaultValue lt T gt  string valueToParse  where T   struct  IComparable    if string EmptyOrNull valueToParse  return null    try             return parsed value      return  T  Convert ChangeType valueToParse  typeof T          catch Exception           default as null value    return null       return null

User · Answer

You could use Convert ChangeType     public static T ConfigSetting lt T gt  string settingName        return  T Convert ChangeType ConfigurationManager AppSettings settingName   typeof T

User · Answer

Create a function and pass out put parameter as of generic type    public static T some function lt T gt  T out put object   declare as Output object                  return out put object

[c#] How do I make the return type of a method generic?

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