This topic has not yet been rated - Rate this topic

CA2208: Instantiate argument exceptions correctly

Visual Studio 2010

TypeName	InstantiateArgumentExceptionsCorrectly
CheckId	CA2208
Category	Microsoft.Usage
Breaking Change	Non Breaking

Cause

Possible causes include the following situations:

A call is made to the default (parameterless) constructor of an exception type that is, or derives from [System.ArgumentException].
An incorrect string argument is passed to a parameterized constructor of an exception type that is, or derives from [System.ArgumentException.]

Rule Description

Instead of calling the default constructor, call one of the constructor overloads that allows a more meaningful exception message to be provided. The exception message should target the developer and clearly explain the error condition and how to correct or avoid the exception.

The signatures of the one and two string constructors of ArgumentException and its derived types are not consistent with respect to the message and paramName parameters. Make sure these constructors are called with the correct string arguments. The signatures are as follows:

ArgumentException (string message)

ArgumentException (string message, string paramName)

ArgumentNullException (string paramName)

ArgumentNullException (string paramName, string message)

ArgumentOutOfRangeException (string paramName)

ArgumentOutOfRangeException (string paramName, string message)

DuplicateWaitObjectException (string parameterName)

DuplicateWaitObjectException (string parameterName, string message)

How to Fix Violations

To fix a violation of this rule, call a constructor that takes a message, a parameter name, or both, and make sure the arguments are proper for the type of ArgumentException being called.

When to Suppress Warnings

It is safe to suppress a warning from this rule only if a parameterized constructor is called with the correct string arguments.

Example

The following example shows a constructor that incorrectly instantiates an instance of the ArgumentNullException type.

C++

Copy


using System;

namespace Samples1
{    
    public class Book    
    {        
        private readonly string _Title;

        public Book(string title)        
        {            
            // Violates this rule (constructor arguments are switched)            
            if (title == null)                
                throw new ArgumentNullException("title cannot be a null reference (Nothing in Visual Basic)", "title");

            _Title = title;        
        }

        public string Title        
        {            
            get { return _Title; }        
        }
    }
}

The following example fixes the above violation by switching the constructor arguments.

C++

Copy


namespace Samples2
{    
    public class Book    
    {        
        private readonly string _Title;

        public Book(string title)        
        {            
            if (title == null)                
                throw new ArgumentNullException("title", "title cannot be a null reference (Nothing in Visual Basic)");

            _Title = title;        }

        public string Title        
        {            
            get { return _Title; }        
        }
    }
}

Did you find this helpful? Yes No

Not accurate

Not enough depth

Need more code examples

(1500 characters remaining)

Community Content Add

FAQ

CA2208 and the C# Property set accessor

The C# compiler translates a set accessor of a property with the name "MyProp" into a method with the signature "... void set_MyProp(string 'value') ..." in MSIL. Therefore to satisfy CA2208, just give the string "value" for paramName.

History

8/12/2010
Simon4