Remove unnecessary lambda expression (IDE0200)
Property | Value |
---|---|
Rule ID | IDE0200 |
Title | Remove unnecessary lambda expression |
Category | Style |
Subcategory | Language rules (code-block preferences) |
Applicable languages | C# 11+ |
Options | csharp_style_prefer_method_group_conversion |
Overview
This rule flags the use of a lambda expression where it's unnecessary. Lambda expressions might be unnecessary when the following are all true:
- The expression includes a method invocation.
- The lambda expression has the same number and order of parameters as the method invocation.
- The method invocation has no side effects.
- The lambda expression isn't assigned to a non-delegate type.
- If the invocation is a generic method, the type arguments are supplied.
- The invoked method's return type can be converted to the lambda expression's return type.
- There's only one applicable method in the method group.
Options
Options specify the behavior that you want the rule to enforce. For information about configuring options, see Option format.
csharp_style_prefer_method_group_conversion
Property | Value | Description |
---|---|---|
Option name | csharp_style_prefer_method_group_conversion | |
Option values | true |
Prefer to convert a lambda expression to a method group. |
false |
Disables the rule. | |
Default option value | true |
Example
// Code with violations.
bool IsEven(int x) => x % 2 == 0;
_ = new[] { 1, 2, 3 }.Where(n => IsEven(n));
// Fixed code.
bool IsEven(int x) => x % 2 == 0;
_ = new[] { 1, 2, 3 }.Where(IsEven);
Suppress a warning
If you want to suppress only a single violation, add preprocessor directives to your source file to disable and then re-enable the rule.
#pragma warning disable IDE0200
// The code that's violating the rule is on this line.
#pragma warning restore IDE0200
To disable the rule for a file, folder, or project, set its severity to none
in the configuration file.
[*.{cs,vb}]
dotnet_diagnostic.IDE0200.severity = none
To disable all of the code-style rules, set the severity for the category Style
to none
in the configuration file.
[*.{cs,vb}]
dotnet_analyzer_diagnostic.category-Style.severity = none
For more information, see How to suppress code analysis warnings.
See also
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