c# 条件编译 Conditional ("DEBUG")

c# 条件编译 Conditional ("DEBUG")

简而言之：可以通过Conditional 指定函数和属性是否编译到最终产品中去。同时还应该看看 AttributeUsage Obsolete

C# Language Specification

System.AttributeUsageAttribute

(Section 17.4.1), which is used to describe the ways in which an attribute class can be used.

System.Diagnostics.ConditionalAttribute

(Section 17.4.2), which is used to define conditional methods.

System.ObsoleteAttribute

(Section 17.4.3), which is used to mark a member as obsolete.

//z 2012-2-24 17:47:38 PM is2120@csdn

利用 Conditional 属性，程序员可以定义条件方法。Conditional 属性通过测试条件编译符号来确定适用的条件。当运行到一个条件方法调用时，是否执行该调用，要根据出现该

调用时是否已定义了此符号来确定。如果定义了此符号，则执行该调用；否则省略该调用（包括对调用的参数的计算）。

条件方法要受到以下限制：

条件方法必须是类声明或结构声明中的方法。如果在接口声明中的方法上指定 Conditional 属性，将出现编译时错误。

条件方法必须具有 void 返回类型。

不能用 override 修饰符标记条件方法。但是，可以用 virtual 修饰符标记条件方法。此类方法的重写方法隐含为有条件的方法，而且不能用 Conditional 属性显式标记。

条件方法不能是接口方法的实现。否则将发生编译时错误。

A conditional method is subject to the following restrictions:

The conditional method must be a method in a class or struct declaration. A compile-time error occurs if the

Conditional

attribute is specified on a method in an interface declaration.
The conditional method must have a return type of

void

.
The conditional method must not be marked with the

override

modifier. A conditional method may be marked with the

virtual

modifier, however. Overrides of such a method are implicitly conditional, and must not
be explicitly marked with a

Conditional

attribute.
The conditional method must not be an implementation of an interface method. Otherwise, a compile-time error occurs.

In addition, a compile-time error occurs if a conditional method is used in a
delegate-creation-expression.

//z 2012-2-24 17:47:38 PM is2120@csdn

示例1：

// CondMethod.cs

// compile with: /target:library /d:DEBUG

using System;

using System.Diagnostics;

namespace TraceFunctions

{

public class Trace

{

[Conditional("DEBUG")]

public static void Message(string traceMessage)

{

Console.WriteLine("[TRACE] - " + traceMessage);

}

}

}

示例2：

using

System;

using System.Diagnostics;

public class Trace

{

[Conditional( "DEBUG" )]

public Static void ShowMessage( string msg)

{

Console.WriteLine( " [Trace - " + msg);

}

}

public class Program

{

public static void Main()

{

Trace.ShowMessage( "Starting" );

Console.WriteLine( "运行中" );

Trace.ShowMessage( "Ending" );

}

}

//z 2012-2-24 17:47:38 PM is2120@csdn