CA1043: Use integral or string argument for indexers
| Property | Value |
|---|---|
| Rule ID | CA1043 |
| Title | Use integral or string argument for indexers |
| Category | Design |
| Fix is breaking or non-breaking | Breaking |
| Enabled by default in .NET 8 | No |
Cause
A type contains an indexer that uses an index type other than System.Int32, System.Int64, System.Object, or System.String.
By default, this rule only looks at externally visible types, but this is configurable.
Rule description
Indexers, that is, indexed properties, should use integer or string types for the index. These types are typically used for indexing data structures and increase the usability of the library. Use of the Object type should be restricted to those cases where the specific integer or string type cannot be specified at design time. If the design requires other types for the index, reconsider whether the type represents a logical data store. If it does not represent a logical data store, use a method.
How to fix violations
To fix a violation of this rule, change the index to an integer or string type or use a method instead of the indexer.
When to suppress warnings
Suppress a warning from this rule only after carefully considering the need for the nonstandard indexer.
Suppress a warning
If you just want to suppress a single violation, add preprocessor directives to your source file to disable and then re-enable the rule.
#pragma warning disable CA1043
// The code that's violating the rule is on this line.
#pragma warning restore CA1043
To disable the rule for a file, folder, or project, set its severity to none in the configuration file.
[*.{cs,vb}]
dotnet_diagnostic.CA1043.severity = none
For more information, see How to suppress code analysis warnings.
Configure code to analyze
Use the following option to configure which parts of your codebase to run this rule on.
You can configure this option for just this rule, for all rules it applies to, or for all rules in this category (Design) that it applies to. For more information, see Code quality rule configuration options.
Include specific API surfaces
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.CAXXXX.api_surface = private, internal
Example
The following example shows an indexer that uses an Int32 index.
string[] Month = new string[] { "Jan", "Feb", "..." };
public string this[int index]
{
get => Month[index];
}
Private month() As String = {"Jan", "Feb", "..."}
Default ReadOnly Property Item(index As Integer) As String
Get
Return month(index)
End Get
End Property
