remove this useless assignment to local variable c#

Remove this useless assignment to variable

I am using SimpleDataTables JS Library and their minimal suggested implementation: const dataTable = new DataTable("#myTable");

In SC this throws me an Remove this useless assignment to variable "dataTable". and an Remove the declaration of the unused 'dataTable' variable.

If I remove the assignement SC tells me to Either remove this useless object instantiation of "DataTable" or use it.

In SC, the FIRST approach is considered a code-smell, the second approach is considered a bug. So I prefer to use first approach, but still SC is not fully happy.

With my rather limited knowledge of JS, I would say simply doing new DataTable("#myTable"); is the right approach. Of course, strictly speaking, that library should probably not have sideffects when instantiating the object but rather provide a method (like DataTable->run()), but that is not the case.

Is there some other approach to do it “correctly” other than marking this as a false alarm?

Indeed you are using some lib probably having side-effects on constructor execution. I don’t think we will support this lib (I see from npm downloads it’s not very popular), so it’s up to you to ignore the issues.

I would keep the variable (it seems the recommended way as you might hook some events on it later). So either you could “won’t fix” the issues, or you can set in SC settings to ignore particular files for these rules (Administration → General Settings → Analysis Scope → Ignore Issues on Multiple Criteria).

Understood, I will maybe switch to the official data tables lib by jQuery. I had chosen the current one because it is much lighter, but in the end with modern computers and servers etc this doesn’t matter that much anyway.

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SonarQube displaying to 'remove this useless assignment to local variable'

Why is SonarQube giving this error? How should I fix it? Their rule page does not specify the solution,

Remove this useless assignment to local variable validateAddressRequest.

 Answers

This site says that the error occurs when:

A value is assigned to a variable or property, but either that location is never read later on, or its value is always overwritten before being read. This means that the original assignment has no effect, and could indicate a logic error or incomplete code.

On the first line of the if block, you assign to validateAddressRequest , but then on the third line of the if block, you overwrite validateAddressRequest without having read the previously assigned variable. So the first line is useless.

Declare validateAddressRequest only when calling convertToValidateRequest instead.

Note that you almost certainly don't need the type annotation - if Typescript knows that convertToValidateRequest returns a ValidateAddressRequest already, there's no need to do so again with the new variable. You can do so if you think it's unclear otherwise, or if you don't have type Intellisense, but it may just be noise.

If you were declaring the variable with let so as to enable assignment to it in the future, keep in mind that it's best to avoid reassignment whenever possible, and it's almost always possible to avoid reassignment. If you need another variable that contains a ValidateAddressRequest , give it a different variable name so that you can use const to declare both variables; that makes the code more understandable at a glance, when a reader can be sure that a particular variable reference isn't ever going to be reassigned.

freddiejarretk

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CA1804: Remove unused locals

• 9 contributors

A method declares a local variable but does not use the variable except possibly as the recipient of an assignment statement. For analysis by this rule, the tested assembly must be built with debugging information and the associated program database (.pdb) file must be available.

Rule description

Unused local variables and unnecessary assignments increase the size of an assembly and decrease performance.

How to fix violations

To fix a violation of this rule, remove, or use the local variable.

The C# compiler removes unused local variables when the optimize option is enabled.

When to suppress warnings

Suppress a warning from this rule if the variable was compiler emitted. It is also safe to suppress a warning from this rule, or to disable the rule, if performance and code maintenance are not primary concerns.

The following example shows several unused local variables.

Related rules

CA1809: Avoid excessive locals

CA1811: Avoid uncalled private code

CA1812: Avoid uninstantiated internal classes

CA1801: Review unused parameters

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Useless assignment to local variable ¶

Click to see the query in the CodeQL repository

A value is assigned to a variable, but either it is never read, or its value is always overwritten before being read. This means that the original assignment has no effect, and could indicate a logic error or incomplete code.

Recommendation ¶

Remove assignments to variables that are immediately overwritten, or use the blank identifier _ as a placeholder for return values that are never used.

In the following example, a value is assigned to a , but then immediately overwritten, a value is assigned to b and never used, and finally, the results of a call to fmt.Println are assigned to two temporary variables, which are then immediately overwritten by a call to function .

The result of calculateValue is never used, and if calculateValue is a side-effect free function, those assignments can be removed. To ignore all the return values of fmt.Println , you can simply not assign it to any variables. To ignore only certain return values, use _ .

References ¶

Wikipedia: Dead store .

The Go Programming Language Specification: Blank identifier .

Common Weakness Enumeration: CWE-563 .

Solving Sonar's 'Remove Useless Assignment of Local Variable' Error in Swift

Abstract: Learn how to resolve SonarQube's 'Remove Useless Assignment of Local Variable' error in Swift by understanding its cause and using different workarounds.

Solving Sonar's "Remove Useless Assignment to Local Variable" Error in Swift

Sonar is a popular tool used for code analysis and review. It helps developers identify and fix issues in their code, making it more readable, maintainable, and secure. One common issue that Sonar flags is the "Remove Useless Assignment to Local Variable" error in Swift. This error occurs when a local variable is assigned a value that is not used in the code. In this article, we will discuss how to solve this error in Swift.

Understanding the Error

To understand the error, let's consider an example:

In this example, we declare two local variables, x and y. We assign the value 5 to x and then calculate the value of y by multiplying x by 2. However, we never use the value of x again in the code. Therefore, Sonar flags the assignment of x as a useless assignment.

Solving the Error

To solve the error, we need to ensure that every local variable is used in the code. We can do this by either using the variable or removing its declaration. In the above example, we can remove the declaration of x, as it is not used in the code:

Alternatively, we can use the value of x in the code:

In this example, we print the value of x to the console, ensuring that it is used in the code.

Using Sonar to Identify Useless Assignments

Sonar can help us identify useless assignments in our code. To do this, we need to configure Sonar to analyze our Swift code. We can do this by installing the SonarSwift plugin and configuring it to analyze our project. Once we have done this, Sonar will flag any useless assignments in our code, allowing us to fix them.

The "Remove Useless Assignment to Local Variable" error in Swift is a common issue that Sonar flags. To solve this error, we need to ensure that every local variable is used in the code. We can do this by either using the variable or removing its declaration. Sonar can help us identify useless assignments in our code, allowing us to fix them and improve the quality of our code.

Remove Useless Assignment to Local Variable

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Tags: :  Swift SonarQube Software Development

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