Can CodeDom create optional arguments when generating a c# method?

Question

Can CodeDom create optional arguments when generating a c# method and provide a default value?

For example:

public void ExampleMethod(int required
                          , string optionalstr = "default string"
                          , int optionalint = 10)

---

Solution I've found a simple workaround for this, you can just put the default value in as part of the argument name:

CodeParameterDeclarationExpression(typeof(int), "optionalint = 5");

This works for me b/c I'm only using the CodeDom to produce C# code. It won't work if you need to support multiple languages.

Enravish

Note that just because you can do this doesn't mean it's a good idea :) – Eastward

I'm surprised that that doesn't give an error. – Spinescent

Answer 1

Yes.

Add the [Optional] attribute.
To specify the default value, add the [[DefaultParameterValue(...)] attribute. (If the default value is 0 or null, this attribute can be omitted.

I wrote a more detailed explanation on my blog.

Spinescent

Can I provide a default value? (Just updated the question for more details about this) I'd like to give a string value (for example) a default value instead of it just passing null. – Enravish

@Not: Yes. Add the [DefaultParameterValue] attribute. – Spinescent

Yep, those work, thanks. Resharper doesn't like it though =( I wish there was a way to make it output in the , int optional = 5) format. – Enravish

@Not: That's a bug in Resharper. You should report it. – Spinescent