Question

Several places in my code a serviceurl is retrievet from app.config like this ConfigurationManager.AppSettings["ServerURL"];

Now I would like to make it possible to the users to specify the service url as a commandline argument. If no argument is specified the serviceurl from app.config must be used.

In Main I can do the following:

if(args[0] != null)
ConfigurationManager.AppSettings["ServerURL"] = args[0]

It seems to work, but can i rely on that AppSettings[“ServerURL”] isnt reloaded from app.config? I know about ConfigurationManager.RefreshSection but it isnt used.

Answer 1

Instead of changing the AppSettings values from code, you should have another class that wraps ConfigurationManager and provides the logic for the value replacement:

public static class Conf {
    public static string ServerURLOverride { get; set; }

    public static string ServerUrl {
        get { return ServerURLOverride ?? ConfigurationManager.AppSettings["ServerURL"]; }
    }
}

And in Main():

if (args.Length > 0 && args[0] != null)
    Conf.ServerURLOverride = args[0];

This will also simplify unit testing.