CODEWITHSUNDEEP
c#app-configdefault-parameterscompile-time-constant
eriyg
eriyg

Reputation: 147

Is hacking an app config value as a default parameter a code smell?

I'm trying to use App.config and Configuration Manager for the first time. I wanted to use some values in App.config as default parameters for some methods, but this results in an error (not a compile time constant):

public void ThisDoesntWork(string parameter = ConfigurationManager.AppSettings["SettingName"])
{
    // Error: not a compile time constant.
}

I kind of understand why this is the case, so I found this workaround:

public void ThisWorks(string parameter = "Use App.config")
{
    if(parameter == "Use App.config")
    {
        parameter = ConfigurationManager.AppSettings["SettingName"]
    }
    // Rest of method.
}

It should be noted that this could also be used to make the return value of a static method (or anything that isn't a compile time constant) a default parameter's value.

This feels a little odd to me and I was wondering if this was a code smell.

Has anyone used this workaround before and run into any issues? What is the best practice in this situation?

How can I use configuration values as a defaults of parameters of my methods without using hacks and creating code smell?

Upvotes: -1

Views: 143

Answers (1)

Dusan
Dusan

Reputation: 5144

Rather than using hacks via magic string/null - you should simply create two overloads of your method.

First one that is parameter-less and uses value from app.config to call the second one (which has required parameter without default value).

Nice and clean and eliminates confusion/ambiguity.

Upvotes: 0

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