使用 vs 2010 中文试用版 编译 Yi Zhang 老师的例子 ，例子博客地址：http://blogs.msdn.com/b/yizhang/archive/2009/08/20/net-4-0-design-by-contracts.aspx
编译后 所有的契约好像都没有效果代码如下：
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Diagnostics.Contracts;
namespace 测试
{
/// <summary>
/// 一个契约式编程的案例。
/// </summary>
public class WordList
{
private List<string> _words;
public WordList(int capacity)
{
Contract.Requires(capacity > 0);
_words = new List<string>(capacity);
}
public void Insert(string word)
{
Contract.Requires(word != null);//检测输入的参数是否复合规则。
Contract.Ensures(Contract.OldValue<int>(_words.Count) + 1 == _words.Count); //这里是检测函数的出口，以保证正确。注意OldValue不完全代表函数的参数，也可以是其它的变量。
Contract.EnsuresOnThrow<ApplicationException>(Contract.OldValue<int>(_words.Count) == _words.Count);//这里表示如果是以抛出表达式相同的异常为函数的出口，那么必须保证表达式中条件。
int i;
for (i = 0; i < _words.Count; i++)
{
int compare= string.Compare(word,_words[i]);
if (compare > 0)
break;
else if (compare == 0)
throw new ApplicationException("Already exist!");
}
_words.Insert(i, word);
}
[ContractInvariantMethod]
internal void Invariant()
{
Contract.Invariant(Contract.ForAll(_words, w => w != null)); //不能有空的字符串。
Contract.Invariant(IsAscending()); //表示必须满足升序条件。
}
[Pure]//这个表示让契约检测来忽略此方法，表示告诉契约这个函数不会对这个对象的元素产生任何副作用。
internal bool IsAscending()
{
bool isAscending = true;
for (int i = 1; i < _words.Count; ++i)
{
if (string.Compare(_words[i - 1], _words[i]) > 0)
{
isAscending = false;
break;
}
}
return isAscending;
}
}
class 契约式编程
{
static void Main(string[] args)
{
//这里有意违反契约规定来测试用。
WordList wl = new WordList(0);
wl.Insert("Hello");
wl.Insert("World");
Console.ReadKey(true);
}
}
}
实际在反编译中，没有任何 契约的代码，而且运行时也不提示错误。
.class public auto ansi beforefieldinit WordList
extends [mscorlib]System.Object
{
.method public hidebysig specialname rtspecialname instance void .ctor(int32 capacity) cil managed
{
.maxstack 8
L_0000: ldarg.0
L_0001: call instance void [mscorlib]System.Object::.ctor()
L_0006: nop
L_0007: nop
L_0008: ldarg.0
L_0009: ldarg.1
L_000a: newobj instance void [mscorlib]System.Collections.Generic.List`1<string>::.ctor(int32)
L_000f: stfld class [mscorlib]System.Collections.Generic.List`1<string> 测试.WordList::_words
L_0014: nop
L_0015: ret
}
.method public hidebysig instance void Insert(string word) cil managed
{
.maxstack 3
.locals init (
[0] int32 i,
[1] int32 compare,
[2] bool CS$4$0000)
L_0000: nop
L_0001: ldc.i4.0
L_0002: stloc.0
L_0003: br.s L_0041
L_0005: nop
L_0006: ldarg.1
L_0007: ldarg.0
L_0008: ldfld class [mscorlib]System.Collections.Generic.List`1<string> 测试.WordList::_words
L_000d: ldloc.0
L_000e: callvirt instance !0 [mscorlib]System.Collections.Generic.List`1<string>::get_Item(int32)
L_0013: call int32 [mscorlib]System.String::Compare(string, string)
L_0018: stloc.1
L_0019: ldloc.1
L_001a: ldc.i4.0
L_001b: cgt
L_001d: ldc.i4.0
L_001e: ceq
L_0020: stloc.2
L_0021: ldloc.2
L_0022: brtrue.s L_0026
L_0024: br.s L_0053
L_0026: ldloc.1
L_0027: ldc.i4.0
L_0028: ceq
L_002a: ldc.i4.0
L_002b: ceq
L_002d: stloc.2
L_002e: ldloc.2
L_002f: brtrue.s L_003c
L_0031: ldstr "Already exist!"
L_0036: newobj instance void [mscorlib]System.ApplicationException::.ctor(string)
L_003b: throw
L_003c: nop
L_003d: ldloc.0
L_003e: ldc.i4.1
L_003f: add
L_0040: stloc.0
L_0041: ldloc.0
L_0042: ldarg.0
L_0043: ldfld class [mscorlib]System.Collections.Generic.List`1<string> 测试.WordList::_words
L_0048: callvirt instance int32 [mscorlib]System.Collections.Generic.List`1<string>::get_Count()
L_004d: clt
L_004f: stloc.2
L_0050: ldloc.2
L_0051: brtrue.s L_0005
L_0053: ldarg.0
L_0054: ldfld class [mscorlib]System.Collections.Generic.List`1<string> 测试.WordList::_words
L_0059: ldloc.0
L_005a: ldarg.1
L_005b: callvirt instance void [mscorlib]System.Collections.Generic.List`1<string>::Insert(int32, !0)
L_0060: nop
L_0061: ret
}
.method assembly hidebysig instance void Invariant() cil managed
{
.maxstack 8
L_0000: nop
L_0001: ret
}
.method assembly hidebysig instance bool IsAscending() cil managed
{
.maxstack 3
.locals init (
[0] bool isAscending,
[1] int32 i,
[2] bool CS$1$0000,
[3] bool CS$4$0001)
L_0000: nop
L_0001: ldc.i4.1
L_0002: stloc.0
L_0003: ldc.i4.1
L_0004: stloc.1
L_0005: br.s L_003b
L_0007: nop
L_0008: ldarg.0
L_0009: ldfld class [mscorlib]System.Collections.Generic.List`1<string> 测试.WordList::_words
L_000e: ldloc.1
L_000f: ldc.i4.1
L_0010: sub
L_0011: callvirt instance !0 [mscorlib]System.Collections.Generic.List`1<string>::get_Item(int32)
L_0016: ldarg.0
L_0017: ldfld class [mscorlib]System.Collections.Generic.List`1<string> 测试.WordList::_words
L_001c: ldloc.1
L_001d: callvirt instance !0 [mscorlib]System.Collections.Generic.List`1<string>::get_Item(int32)
L_0022: call int32 [mscorlib]System.String::Compare(string, string)
L_0027: ldc.i4.0
L_0028: cgt
L_002a: ldc.i4.0
L_002b: ceq
L_002d: stloc.3
L_002e: ldloc.3
L_002f: brtrue.s L_0036
L_0031: nop
L_0032: ldc.i4.0
L_0033: stloc.0
L_0034: br.s L_004d
L_0036: nop
L_0037: ldloc.1
L_0038: ldc.i4.1
L_0039: add
L_003a: stloc.1
L_003b: ldloc.1
L_003c: ldarg.0
L_003d: ldfld class [mscorlib]System.Collections.Generic.List`1<string> 测试.WordList::_words
L_0042: callvirt instance int32 [mscorlib]System.Collections.Generic.List`1<string>::get_Count()
L_0047: clt
L_0049: stloc.3
L_004a: ldloc.3
L_004b: brtrue.s L_0007
L_004d: ldloc.0
L_004e: stloc.2
L_004f: br.s L_0051
L_0051: ldloc.2
L_0052: ret
}
.field private class [mscorlib]System.Collections.Generic.List`1<string> _words
}
请高人解答，是不是我漏了什么设置之类的东西。
