Use expression body for properties (IDE0025)

Статия
09/16/2023

Property	Value
Rule ID	IDE0025
Title	Use expression body for properties
Category	Style
Subcategory	Language rules (expression-bodied members)
Applicable languages	C#
Options	`csharp_style_expression_bodied_properties`

Overview

This style rule concerns the use of expression bodies versus block bodies for properties.

Options

Set the value of the associated option for this rule to specify whether expression bodies or block bodies for properties are preferred, and if expression bodies are preferred, whether they're preferred only for single-line expressions.

For more information about configuring options, see Option format.

csharp_style_expression_bodied_properties

Property	Value	Description
Option name	csharp_style_expression_bodied_properties
Option values	`true`	Prefer expression bodies for properties
	`when_on_single_line`	Prefer expression bodies for properties when they will be a single line
	`false`	Prefer block bodies for properties
Default option value	`true`

// csharp_style_expression_bodied_properties = true
public int Age => _age;

// csharp_style_expression_bodied_properties = false
public int Age { get { return _age; }}

This rule versus IDE0027

This rule, IDE0025, and IDE0027 (Use expression body for accessors) are very similar. IDE0025 concerns the property as a whole, whereas IDE0027 specifically concerns the accessor parts of the property.

For a read-only property that simply returns a value without doing any computation, if IDE0025 is set to csharp_style_expression_bodied_properties = false but IDE0027 is set to csharp_style_expression_bodied_accessors = true, you end up with a property that looks like this:

public int TemperatureF
{
    get => _temp;
}

But if you set IDE0025 to csharp_style_expression_bodied_properties = true, the property is simplified even further (even if you set IDE0027 to csharp_style_expression_bodied_accessors = false):

public int TemperatureF => _temp;

For a read-write property, the difference becomes a little more apparent, because the property can't be written in an expression-bodied manner (because it consists of more than one line). So even if IDE0025 is set to csharp_style_expression_bodied_properties = true, you still end up with curly braces, that is, a block body.

The following examples show how a property looks with various combinations of the two options.

// csharp_style_expression_bodied_properties = false
// csharp_style_expression_bodied_accessors = true
public int TemperatureB
{
    get => _temp;
}

// csharp_style_expression_bodied_properties = true
// csharp_style_expression_bodied_accessors = true (or false)
public int TemperatureC => _temp;

// csharp_style_expression_bodied_properties = true (or false)
// csharp_style_expression_bodied_accessors = true
public int TemperatureD
{
    get => _temp;
    set => _temp = value;
}

// csharp_style_expression_bodied_properties = true
// csharp_style_expression_bodied_accessors = false
public int TemperatureE
{
    get
    {
        return _temp;
    }
    set
    {
        _temp = value;
    }
}

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 IDE0025
// The code that's violating the rule is on this line.
#pragma warning restore IDE0025

To disable the rule for a file, folder, or project, set its severity to none in the configuration file.

[*.{cs,vb}]
dotnet_diagnostic.IDE0025.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.

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