C# !Conditional attribute?

Question

Does C# have a not Conditional (!Conditional, NotConditional, Conditional(!)) attribute?

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i know C# has a Conditional attribute:

[Conditional("ShowDebugString")] public static void ShowDebugString(string s) {    ... } 

which is equivalent¹ to:

public static void ShowDebugString(string s) { #if ShowDebugString    ... #endif } 

But in this case i want the inverse behavior (you have to specifically opt out):

public static void ShowDebugString(string s) { #if !RemoveSDS    ... #endif } 

Which leads me to try:

[!Conditional("RemoveSDS")] public static void ShowDebugString(string s) {    ... } 

which doesn't compile. And:

[Conditional("!RemoveSDS")] public static void ShowDebugString(string s) {    ... } 

which doesn't compile. And:

[NotConditional("RemoveSDS")] public static void ShowDebugString(string s) {    ... } 

which doesn't compile because it's only wishful thinking.

¹Not true, but true enough. Don't make me bring back the Nitpicker's Corner. ^🕗

Answer 1

First, having the Conditional attribute is not equivalent to having #if inside the method. Consider:

ShowDebugString(MethodThatTakesAges()); 

With the real behaviour of ConditionalAttribute, MethodThatTakesAges doesn't get called - the entire call including argument evaluation is removed from the compiler.

Of course the other point is that it depends on the compile-time preprocessor symbols at the compile time of the caller, not of the method :)

But no, I don't believe there's anything which does what you want here. I've just checked the C# spec section which deals with conditional methods and conditional attribute classes, and there's nothing in there suggesting there's any such mechanism.

Answer 2

Nope.

Instead, you can write

#if !ShowDebugString [Conditional("FALSE")] #endif 

Note that unlike [Conditional], this will be determined by the presence of the symbol in your assembly, not in your caller's assembly.