要检查的第一件事-您是否已打开合同检查功能？如果没有，您的任何合同都不会做任何事情。那也将解释R＃警告。在构建属性的代码合同下查看，并在运行时检查下查看其内容。

First thing to check - have you actually got contract checking turned on? If not, none of your contracts will do anything. That would explain the R# warning, too. Look under "Code Contracts" in the build properties, and see what it says under "Runtime Checking".

根据注释，确保您有 CONTRACTS_FULL 定义为编译符号-似乎是R＃所需要的。

As per comments, ensure you have CONTRACTS_FULL defined as a compilation symbol - that appears to be what R# requires.

第二点：您有公共可变字段，该字段是表示有人在任何时候都会侵犯您的不变式

Second point: you've got public mutable fields, which means your invariant can be violated at any moment by someone writing

polygon.VertexCount = 0;

请不要使用公共字段，尤其是不可写的字段。 ：）

Please don't use public fields, particularly not writable ones. :)