Default parameters in C#

re: Default parameters in C#

Ryan CrawCour — Tue, 22 Mar 2011 13:24:11 GMT

You raise some interesting points here; points i have myself considered and pondered. Are default parameters a blessing? Or a curse?

re: Default parameters in C#

Marc Brooks — Fri, 25 Feb 2011 05:58:11 GMT

I swore to my teddy bear to NEVER add an override that takes a boolean. I've found over the years that the meaning of true or false is so easily lost, and so easily forgotten which is the "without argument" state that I've gone to using an Enum that clearly described the behavior.

Years later:

var tweets = TweetRepo.GetLatestTweets(tweepId, DirtyWords.ReplaceNaughty);

Is much clearer than:

var tweets = TweetRepo.GetLatestTweets(tweepId, true);

re: Default parameters in C#

Shuggy — Thu, 24 Feb 2011 10:32:48 GMT

The thing I don't like is that they are most useful as a replacement for a bunch of overloads _but_ the semantics of the defaults is different. Instead of being baked into the dll that defines them they are backed into the dlls that compile against them.

If you make heavy use of overloads to maintain binary compatibility then it's a real pain.

I really wish there was a simple way to just create overloads that deferred to the others (and could have xdoc links to the master one (along with an indication of what the defaults were)

some thing like:

///<docref cref="Frob(int,string)"><paramref name="s"> is string.Empty</docref>

public Foo Frob(int x)

{

return Frob(x, string.Empty);

}

///<summary>blah blah blah</summary>

public Foo Frob(int x, string s)

{

}

note how the paramref is refering to a parameter on the master, not the current method

for overloads using compile time literals you could do very terse stuff like:

public overload Foo Frob(int x) ~> Frob(x, "");

And have the document system auto fill everything for you. Though often being limited to compile time literals would be a pain I image it would in fact cover 70% of my needs (so long as default(T) was allowed on generic methods).

And hey, I found a use for the nadj (blogs.msdn.com/.../a-face-made-for-email-part-four.aspx) :)

re: Default parameters in C#

Haacked — Thu, 24 Feb 2011 05:26:12 GMT

There's definitely some versioning issues to consider when using optional parameters with defaults.

haacked.com/.../versioning-issues-with-optional-arguments.aspx

haacked.com/.../more-optional-versioning-fun.aspx

This led us to remove much of our usage of them in ASP.NET except for maybe a few places where we didn't think we'd ever change them.