What code contracts provide is a mean to check that some statements, like:<\/p>\n
- \n
- maximum value of the range should always be greater than the minimum value<\/li>\n
- returned value should always be in the interval, equal or greater than the minimum, and equal or less than then maximum<\/li>\n<\/ul>\n
The first is a pre-requisite, and the second is a post-requisite. We can specify those with:<\/p>\n
\r\n public int GetRandom(int min, int max)\r\n {\r\n Contract.Requires(max > min);\r\n Contract.Ensures(Contract.Result() >= min && \r\n Contract.Result () <= max);\r\n\r\n return rng.Next(min, max);\r\n }\r\n<\/pre>\n The Contract class is available in namespace System.Diagnostics.Contracts. To enable the static checking, you have to go to Project Properties > Code Contracts and select “Perform Static Contract Checking.”<\/p>\n
![\"Code](\"\/blog\/wp-content\/uploads\/2009\/05\/vs2010_codecontractsproperties.png\" "\\"Code")
Code Contracts Property Page<\/figcaption><\/figure>\n When you build, you get the following warnings:
\n![\"Code](\"\/blog\/wp-content\/uploads\/2009\/05\/vs2010_codecontractswarnings.png\" "\\"Code")
Code Contracts warnings<\/figcaption><\/figure><\/p>\n The first says that the call GetRandom(10, 10) does not match the pre-condition. The second warning indicates that the post-condition is not met. It isn’t possible to know whether Random.Next() returns a value that hods the post-condition. But if you check the “Perform Runtime Contract Checking” it asserts at runtime, when the return value is outside the interval (not possible with this code sample).<\/p>\n
You can read more about code contracts on the BCL team’s blog<\/a>. It features a list of possible constructs for pre- and post-requisites, but also object invariants.<\/p>\n
Code Contracts are also available for Visual Studio 2008. For downloads and additional information check the following links:<\/p>\n
- \n
- Code Contracts at DevLabs<\/a><\/li>\n
- Code Contracts at Microsoft Research<\/a><\/li>\n<\/ul>\n
<\/p>\n","protected":false},"excerpt":{"rendered":"
Visual Studio 2010 has support for code contracts that allow to express pre-, post-conditions and invariants to your .NET code. Let’ say you want to create a function to return a random value in a range. This could look like it: class Program { Random rng = new Random(); public int GetRandom(int min, int max) … Read more<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_uag_custom_page_level_css":"","advgb_blocks_editor_width":"","advgb_blocks_columns_visual_guide":"","_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_feature_clip_id":0,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":false,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2},"jetpack_post_was_ever_published":false},"categories":[13,11,20,52,10],"tags":[454,28,451,127,89],"class_list":["post-296","post","type-post","status-publish","format-standard","hentry","category-net","category-csharp","category-ctps-betas","category-tools","category-visual-studio","tag-net","tag-beta","tag-c","tag-code-contracts","tag-vs2010"],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t
- Code Contracts at Microsoft Research<\/a><\/li>\n<\/ul>\n
- Code Contracts at DevLabs<\/a><\/li>\n