How do I make the return type of a method generic?

c# .net generics return-type
MacGyver picture MacGyver · Mar 21, 2012 · Viewed 273.7k times · Source

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];
    }

Answer

Jon Skeet picture Jon Skeet · Mar 21, 2012

You need to make it a generic method, like this:

public static T ConfigSetting<T>(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<T>(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...

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