How to throw a compiler warning/error like [ObsoleteAttribute] does.

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I don't think this is possible, but I have always hoped it is.

When you apply [Obsolete("You really shouldn't use this anymore.")] to a member, it causes the compiler to generate a warning or error, which then appears in the Error List in Visual Studio.

It would be amazing to be able to do this when building components for conditions other obsolescence, even something like: [Experimental("This method is still in development and should not be used in production environments.")] and the like.

Anyone?

FYI: System.ObsoleteAttribute is sealed.

Posted 5-Dec-13 4:02am

Yvan Rodrigues

Updated 5-Dec-13 4:21am

v2

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Ron Beyer · Accepted Answer · 2013-12-05T04:15:00

Solution 1

Unfortunately there is no magic in the ObsoleteAttribute[^] class. The compiler service looks for this attribute and displays the warnings in the dialog box.

However, you can raise warnings yourself, like:

C#

public void MyMethod()
{
#warning This method is still in development and is not recommended for production.
}

See #warning[^]

Posted 5-Dec-13 4:15am

Ron Beyer

Updated 5-Dec-13 4:19am

v3

Comments

Yvan Rodrigues 5-Dec-13 10:21am

You know, I think I knew of #warning and #error years ago, and had completely forgotten about them. It doesn't solve my problem, since I (the component creator) will get the warning, not the end-user, but thanks for reminding me about this.

Ron Beyer 5-Dec-13 10:25am

It really is too bad there isn't something like a WarningAttribute, but the recognition of the ObsoleteAttribute is purely compiler based and not something built into .NET. There are ways to suppress code analysis messages through attributes, but no way to raise warnings through them.

Ron Beyer 5-Dec-13 10:27am

Another alternative is to use the ///summary XML tags to display a message to the user, since this shows up when they use intellisense. Something like:

///<summary>[Experimental] This method does something magical</summary>
public void MyMethod() { }

Yvan Rodrigues 5-Dec-13 10:29am

nice tip!

BillWoodruff 5-Dec-13 20:02pm

+5 Valuable information that had ... uhh ... slipped me mind: thanks, Ron