This is a demo project for Albumprinter BV .Net team.

C# typesystem is limited in some cases, so we might need a tool to express some extra ideas in code.

• Null-NotNull attribute

Demo:

[CanBeNull]
public static string CanReturnNull(string parameter)
{
	var rand = new Random();
    return (rand.Next()%2) == 0 ? "string" : null;
}

• Pure attribute

In computer programming, a function may be described as a pure function if both these statements about the function hold:

1. The function always evaluates the same result value given the same argument value(s). The function result value cannot depend on any hidden information or state that may change as program execution proceeds or between different executions of the program, nor can it depend on any external input from I/O devices.
2. Evaluation of the result does not cause any semantically observable side effect or output, such as mutation of mutable objects or output to I/O devices.

(c) Wikipedia

Demo

public class MyInt
{
	private readonly int value;
	public MyInt(int value)
    {
    	this.value = value;
    }

    public int Value
    {
        get { return value; }
    }
        
    [Pure]
    public MyInt Add(int add)
    {
        return new MyInt(Value + add);
    }
}

• Contracts

[CanBeNull] and [NotNull] does not allow us to express any conditions. So the Method can be either NotNull either CanBeNull. Not both of them.

Demo

public static class ContractTest
{
    [ContractAnnotation("str:null => null;str:notnull=>notnull")]
    public static string Reverse(string str)
    {
        if (str == null) return null;
   		return new string(str.Reverse().ToArray());
    }
}

• [PublicApi], [UsedImplisitly] attributes

Demo

• Resource navigation

Demo

• Custom string formatting

Demo

• How to add Jetbrains.Annotations to you solution. http://www.jetbrains.com/resharper/webhelp/Code_Analysis__Annotations_in_Source_Code.html

• List of attributes http://www.jetbrains.com/resharper/webhelp/Reference__Code_Annotation_Attributes.html

• Contracts http://blog.jetbrains.com/dotnet/2012/08/15/contract-annotations-in-resharper-7

• http://stackoverflow.com/questions/24805040/how-to-ignore-reference-to-jetbrains-annotations-dll-in-nodatime-nuget-package-x

• AspMvc Annotations http://blog.jetbrains.com/dotnet/2011/12/07/providing-intellisense-navigation-and-more-for-custom-helpers-in-aspnet-mvc/