C# 4.0 Code Contracts Microsoft has released a library for design by contract in version 4.0 of the .net framework. One of the coolest features of that library is that it also comes with a static analysis tools (similar to FxCop I guess) that leverages the details of the contracts you place on the code. … Read more
As far as I’ve read from this document: http://www.open-std.org/JTC1/SC22/WG21/docs/papers/2015/n4415.pdf Contracts do what assert has been trying to do in a primitive way for years. They’re both documentation and a run-time assert of how the caller should be expected to call the function and in what state can the caller expect the code to be after … Read more
There is a nice overview on WikiPedia about Design by Contract, at the end there is a section regarding languages with third party support libraries, which includes a nice serie of Java libraries. Most of these Java libraries are based on Java Assertions. In the case you only need Precondition Checking there is also a … Read more
The main problem with DBC is that in the vast majority of cases, either the contract cannot be formally specified (at least not conveniently), or it cannot be checked with current static analysis tool. Until we get past this point for mainstream languages (not Eiffel), DBC will not give the kind of assurance that people … Read more
You should do the following: Install the Code Contracts add-in as nfechner has noted Go to the project properties, ‘Code Contracts’ folder Check ‘Perform Runtime Contract Checking’ Switch ‘Assembly Mode’ to ‘Standard Contract Requires’ Substitute your Contract.Requires with Contract.Requires<SomeException> (the first one throws System.Diagnostics.ContractException while the second throws the exception you specified which is important … Read more
A very good follow up question. I consider null a truly special value, and if a method may return null it must clearly document in the Javadoc when it does (@return some value …, or null if …). When coding I’m defensive, and assume a method may return null unless I’m convinced it can’t (e.g., … Read more
Note: as of the current R# 8.0 EAP, this functionality is included. Here’s the solution for the current (i.e. .NET 4.0) version of Code Contracts: Inside …\ExternalAnnotations\mscorlib\Contracts.xml, add the following: <assembly name=”mscorlib”> <member name=”M:System.Diagnostics.Contracts.Contract.Assert(System.Boolean)”> <attribute ctor=”M:JetBrains.Annotations.AssertionMethodAttribute.#ctor”/> <parameter name=”condition”> <attribute ctor=”M:JetBrains.Annotations.AssertionConditionAttribute.#ctor(JetBrains.Annotations.AssertionConditionType)”> <argument>0</argument> </attribute> </parameter> </member> <member name=”M:System.Diagnostics.Contracts.Contract.Assert(System.Boolean, System.String)”> <attribute ctor=”M:JetBrains.Annotations.AssertionMethodAttribute.#ctor”/> <parameter name=”condition”> <attribute ctor=”M:JetBrains.Annotations.AssertionConditionAttribute.#ctor(JetBrains.Annotations.AssertionConditionType)”> <argument>0</argument> </attribute> … Read more
The first issue you raise is the so-called “fragile test” problem. You make a change to your application, and hundreds of tests break because of that change. When this happens, you have a design problem. Your tests have been designed to be fragile. They have not been sufficiently decoupled from the production code. The solution … Read more
The PEP you found hasn’t yet been accepted, so there isn’t a standard or accepted way of doing this (yet — you could always implement the PEP yourself!). However, there are a few different approaches, as you have found. Probably the most light-weight is just to simply use Python decorators. There’s a set of decorators … Read more
One thing to remember that your code that you write today while it may be a small team and you can have good documentation, will turn into legacy code that someone else will have to maintain. I use the following rules: If I’m writing a public API that will be exposed to others, then I … Read more