確保對象不變？

有沒有使用代碼合同來確保/檢查方法是否不會更改對象的任何成員的方法，類似於C++ const方法或將所有成員設置爲readonly？確保對象不變？

即比以下更簡單的方法：使用Contract.EnsuresOnThrow

Contract.Ensures(this.member1 == Contract.OldValue(this.member1)); 
Contract.Ensures(this.member2 == Contract.OldValue(this.member2)); 
Contract.Ensures(this.member3 == Contract.OldValue(this.member3)); 
Contract.Ensures(this.member4 == Contract.OldValue(this.member4)); 
Contract.Ensures(this.member5 == Contract.OldValue(this.member5));

或相同。

來源

2012-11-21 ronag

可能重複的[C＃：可以參數是不變的？]（http://stackoverflow.com/questions/2339074/c-can-parameters-be-constant） – Sjoerd

@Sjoerd我不認爲這是重複的，因爲這裏的操作是要求具體是否可以通過代碼合同完成。 – McGarnagle

@Sjoerd：我不是問語言/編譯器是否可以執行這個檢查，我知道它不能。我問的是代碼合同靜態/運行時檢查可以做到這一點。 – ronag

所以基本上你想檢查的方法是Pure。該official documentation表明其尚不支持（參見5.4節）：

5.4 Purity 

All methods called within a contract must be pure: that is, they must not update 
any pre-existing state. (A pure method is allowed to modify objects that have been 
created after entry into the pure method.) Code Contract tools currently assume 
the following things are pure: 

* Methods marked [Pure] (If a type is marked [Pure], then that applies to all of 
    its methods.) The pure attribute is dened in the contract library. (Section 4.3) 

* Property getters. 

* Operators (static methods whose names start with op , have one or two parameters 
    and a non-void return type). 

* Any method whose fully qualified name begins with 
    System.Diagnostics.Contracts.Contract, System.String, System.IO.Path, or 
    System.Type. 

* Any invoked delegate, provided that the delegate type itself is attributed with 
    [Pure]. The existing delegate types System.Predicate<T> and System.Comparison<T> 
    are considered pure. 

In the future, there will be a purity checker that will enforce these assumptions.

來源

2012-11-21 10:40:49 Mightymuke

也許你可以包括相應的爲了完成你的答案？ – ronag

@ronag - 對不起，好點。我已將文檔添加到答案中。 – Mightymuke

大概「定義」==「定義」:) – porges

如果你的類實現

ICloneable

和

IEquatable<YourClassType>

的值相等（不引用平等），比你可以這樣寫：

Contract.Ensures( 
    this.Equals (Contract.OldValue ((YourClassType)this.Clone()) 
);

來源

2013-12-09 09:20:05 ddur

確保對象不變？

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