remove this useless assignment to local variable sonar

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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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

Supported Languages

Tags: :  Swift SonarQube Software Development

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java - Sonar "useless assignment to local variable"解决方法？

标签 java null sonarqube sonar-runner

我正在努力改进我的代码，我从 Sonar 遇到了这个问题:

事实是，它并非毫无用处，因为我在代码之后就使用了它:

Sonar 仍然告诉我“uiRequest”没用，为什么？它不是，因为如果它为空，我不希望它到达代码。我尝试初始化它 ( uiRequest = new UiRequest() )，但它一直告诉我它没用。

有人知道为什么 Sonar 会这样/如何纠正吗？

这段代码有两条可能的路径:

• a() 返回 true 。 x 被分配 b() 然后 c(x) 被调用。
• a() 返回 false 。抛出异常， c(x) 没有被调用。

这些路径都没有使用 null 的初始赋值调用 c(x) 。因此，无论您最初分配什么，都是多余的。

请注意，如果初始分配不是 null，这也会是一个问题。除非赋值的右侧有 副作用 ，否则任何赋值都会被浪费。 ( Sonar 分析副作用)

这对 Sonar 来说是可疑的:

• 也许程序员期望第一个赋值会产生效果——它没有，所以这可能是一个错误。
• 这还与代码的清晰度有关—— future 代码的人类读者可能会浪费时间思考初始值的用途。
• 如果右侧涉及计算，但没有副作用，那将是浪费计算。

您可以通过两种方式解决此问题:

首先只是删除 = null ，留下 Foo x; - Java 足够聪明，可以实现所有到 c(x) 的路由涉及赋值，所以这仍然可以编译。

更好的是，将 c(x) 移到 block 中:

这在逻辑上是等价的，更简洁，并且减少了 x 的范围。缩小范围是一件好事。当然，如果你 需要 更大范围的 x ，你就不能这样做了。

还有一个变体，逻辑上也是等价的:

...对“提取方法”和“内联”重构 react 良好:

使用最能传达您意图的那个。

关于java - Sonar "useless assignment to local variable"解决方法？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/44115011/

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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

"Remove this useless assignment to local variable", but the assignment is not useless

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Michael Gumowski

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404 Not found

Sonar issue - Remove this useless assignment to local variable

I am using below mentioned piece of code:

Here sonar is saying "Remove this useless assignment to local variable". How can I add to the list without initializing it with new keyword?

Sonar comment is "Remove this useless assignment to local variable "listComments". "

I went through below links but not getting my answer.

Sonar complaining about useless assignment of local variable

remove this useless assignment to local variable c#

• sonarqube-scan

What about this:

If these are of same type. Otherwise project the required fields after where:

I guess that ForEach loop is unnecessary.

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Remove unused assignments and methods from Major Sonar issues #2059

abhishek-hedera commented Aug 23, 2021

Successfully merging a pull request may close this issue.