如何使方法的返回类型通用? [英] How do I make the return type of a method generic?

问题描述

有没有办法让这个方法通用，这样我就可以返回一个字符串、布尔值、整数或双精度值?现在，它返回一个字符串，但如果它能够找到true"或false"作为配置值，我想返回一个布尔值.

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];
    }

推荐答案

你需要把它变成一个泛型方法，像这样:

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... */
}

但是调用者必须指定他们期望的类型.然后您可以潜在地使用 Convert.ChangeType，假设所有支持相关类型:

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));
}

我并不完全相信这一切都是个好主意，请注意...

I'm not entirely convinced that all this is a good idea, mind you...

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