CA1710: Identifiers should have correct suffix

TypeName IdentifiersShouldHaveCorrectSuffix
CheckId CA1710
Category Microsoft.Naming
Breaking Change Breaking

Cause

An identifier does not have the correct suffix.

By default, this rule only looks at externally visible identifiers, but this is configurable.

Rule description

By convention, the names of types that extend certain base types or that implement certain interfaces, or types derived from these types, have a suffix that is associated with the base type or interface.

Naming conventions provide a common look for libraries that target the common language runtime. This reduces the learning curve that is required for new software libraries, and increases customer confidence that the library was developed by someone who has expertise in developing managed code.

The following table lists the base types and interfaces that have associated suffixes.

Base type/Interface Suffix
System.Attribute Attribute
System.EventArgs EventArgs
System.Exception Exception
System.Collections.ICollection Collection
System.Collections.IDictionary Dictionary
System.Collections.IEnumerable Collection
System.Collections.Queue Collection or Queue
System.Collections.Stack Collection or Stack
System.Collections.Generic.ICollection<T> Collection
System.Collections.Generic.IDictionary<TKey,TValue> Dictionary
System.Data.DataSet DataSet
System.Data.DataTable Collection or DataTable
System.IO.Stream Stream
System.Security.IPermission Permission
System.Security.Policy.IMembershipCondition Condition
An event-handler delegate. EventHandler

Types that implement ICollection and are a generalized type of data structure, such as a dictionary, stack, or queue, are allowed names that provide meaningful information about the intended usage of the type.

Types that implement ICollection and are a collection of specific items have names that end with the word 'Collection'. For example, a collection of Queue objects would have the name 'QueueCollection'. The 'Collection' suffix signifies that the members of the collection can be enumerated by using the foreach (For Each in Visual Basic) statement.

Types that implement IDictionary have names that end with the word 'Dictionary' even if the type also implements IEnumerable or ICollection. The 'Collection' and 'Dictionary' suffix naming conventions enable users to distinguish between the following two enumeration patterns.

Types with the 'Collection' suffix follow this enumeration pattern.

foreach(SomeType x in SomeCollection) { }

Types with the 'Dictionary' suffix follow this enumeration pattern.

foreach(SomeType x in SomeDictionary.Values) { }

A DataSet object consists of a collection of DataTable objects, which consist of collections of System.Data.DataColumn and System.Data.DataRow objects, among others. These collections implement ICollection through the base System.Data.InternalDataCollectionBase class.

How to fix violations

Rename the type so that it is suffixed with the correct term.

When to suppress warnings

It is safe to suppress a warning to use the 'Collection' suffix if the type is a generalized data structure that might be extended or that will hold an arbitrary set of diverse items. In this case, a name that provides meaningful information about the implementation, performance, or other characteristics of the data structure might make sense (for example, BinaryTree). In cases where the type represents a collection of a specific type (for example, StringCollection), do not suppress a warning from this rule because the suffix indicates that the type can be enumerated by using a foreach statement.

For other suffixes, do not suppress a warning from this rule. The suffix allows the intended usage to be evident from the type name.

Configurability

If you're running this rule from FxCop analyzers (and not through static code analysis), you can configure which parts of your codebase to run this rule on, based on their accessibility. For example, to specify that the rule should run only against the non-public API surface, add the following key-value pair to an .editorconfig file in your project:

dotnet_code_quality.ca1710.api_surface = private, internal

You can configure this option for just this rule, for all rules, or for all rules in this category (Naming). For more information, see Configure FxCop analyzers.

CA1711: Identifiers should not have incorrect suffix

See also