Microsoft .NET Code Analysis: Remove Unnecessary Lambda Expressions

Mar 21, 2024 10:04 AM

Microsoft recommends eliminating redundant Lambda expressions. This code exemplifies the issue:

condition = allRequiredNonPkProperties.Select(p => projection.BindProperty(p))
  .Select(c => (SqlExpression)_sqlExpressionFactory.NotEqual(c,
  _sqlExpressionFactory.Constant(null)))
  .Aggregate((a, b) => _sqlExpressionFactory.AndAlso(a, b));

Lambda expressions may be superfluous under the following conditions:

• 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.

Here is how to rectify the aforementioned code:

condition = allRequiredNonPkProperties.Select(projection.BindProperty)
  .Select(c => (SqlExpression)_sqlExpressionFactory.NotEqual(c, 
  _sqlExpressionFactory.Constant(null)))
  .Aggregate((a, b) => _sqlExpressionFactory.AndAlso(a, b));

Here are additional reasons why removing unnecessary Lambda expressions should be undertaken:

1. Efficient Code Reviews: Reducing or eliminating unnecessary Lambda expressions improves the efficiency of code reviews. It minimizes potential points of confusion or discussion during the review process, allowing for quicker and more focused evaluations.
2. Enhanced Code Clarity and Readability: The removal of unnecessary Lambda expressions contributes to code clarity and readability. By eliminating extraneous elements, the code becomes more comprehensible, aiding developers in understanding its purpose and flow.
3. Facilitated Debugging: Unnecessary Lambda expressions can complicate the debugging process. Removing them simplifies the codebase, making it easier to identify and rectify issues during the debugging phase.
4. Optimized Performance: While the impact of an individual Lambda expression on performance is typically minimal, the accumulation of unnecessary Lambdas can lead to a subtle yet measurable decrease in overall performance. Removing them helps optimize the codebase for better efficiency.
5. Simplified Maintenance: Code with fewer unnecessary Lambda expressions is easier to maintain. This streamlined structure facilitates updates, bug fixes, and overall code management, reducing the chances of errors and making maintenance tasks more straightforward.
6. Trimmed Code Size: Unneeded Lambda expressions can contribute to unnecessary code bloat, impacting the size of the compiled code. This is particularly relevant for web applications where smaller file sizes are desirable for faster load times. Removing unnecessary Lambdas helps keep the codebase lean and optimized.

When I setup the IDE0200 code analysis in my .editorConfig it looks like this: dotnet_diagnostic.IDE0200.severity = warning

Summary

While reviewing the Entity Framework codebase I utilized for this article, I discovered 23 occurrences where the code needs to be fixed.

For further guidance and insights, I highly recommend obtaining a copy of my book, “Rock Your Code: Coding Standards for Microsoft .NET” available on Amazon.com. Additionally, to explore more performance tips for .NET, I encourage you to acquire the 3rd edition of “Rock Your Code: Code & App Performance for Microsoft .NET” also available on Amazon.com.

To analyze your code using the same settings I used in these articles, I encourage you to incorporate my EditorConfig file. It can be found at the following link: https://bit.ly/dotNetDaveEditorConfig. I update this file quarterly, so remember to keep yours up to date as well. I hope you will check out my OSS project Spargine by using this link: https://bit.ly/Spargine.

Please feel free to leave a comment below. I would appreciate hearing your thoughts and feedback.

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