C＃Windows Phone XNA应用程序中的可选参数

Question

Is it possible to use optional parameters (and other purely-syntactical C# 4.0 features) in Windows Phone XNA applications?

I've read and heard conflicting information about this. In the Advanced Build Settings for my application, the Language Version is set to C# 3.0 (C# 4.0 is not available in the Language Version drop-down list). Is 3.0 the "official" C# version that's going to be used initially for Windows Phone development?

Am I silly for even expecting C# 4.0 features to be available at all?

Answer 1

Beneath the Silverlight and XNA flair lies some version of the .NET 3.x (3.7?) compact framework. As far behind as Windows Phone 7 is with respect to the rest of the marketplace, this far into the game it's unlikely that a .NET 4.0 compact framework will be inserted (afaik does not yet exist) or any other major architectural changes required to support C# 4.0.

Answer 2

I have found that Optional Parameters work properly in Silverlight but not in XNA. I have been using the #if stuff to get around this in shared code as follows:

#if !SILVERLIGHT
public SomeClass ( ) : this (null)
{
}

public SomeClass(object someParam)

#else

public SomeClass(object someParam = null)

#endif
{
    m_someParam = someParam;
}

But that is a touch ugly. I have also noticed the Add References dialog from the Productivity Power Pack doesn't work with XNA projects, indicating something fishy is going on with XNA projects. [As a side note, I can deploy and debug Silverlight apps to the emulator via VS but NOT XNA apps]

Answer 3

Best solution: make use of function overloading.

Example (causes errors):

public void RenderRadius(SpriteBatch spriteBatch, Entity entity, float radiusOverride = -1)

...

Solution:

public void RenderRadius(SpriteBatch spriteBatch, Entity entity){ RenderRadius(spriteBatch, entity, -1); }
public void RenderRadius(SpriteBatch spriteBatch, Entity entity, float radiusOverride)

...

Super easy. Done.

Answer 4

I'm not sure if it is possible to use the optional parameters with Xna (I've never had the desire to), but you can do what you are talking about.

http://xboxforums.create.msdn.com/forums/p/54007/515654.aspx

At the link above, it says to set your language version to default, rather than C# 3.0. Seems you were on the right track.