CodeNarc - CodeNarc - Unused Rules

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## Unused Rules ("rulesets/unused.xml")

### UnusedArray Rule

Checks for array allocations that are not assigned or used, unless it is the last statement within a block (because it may be the intentional return value). Examples include:

        int myMethod() {
            new String[3]               // unused
            return -1
        }

        String[] myMethod() {
            new String[3]               // OK (last statement in block)
        }

        def closure = {
            doStuff()
            new Date[3]                 // unused
            doOtherStuff()
        }

        def closure = { new Date[3] }   // OK (last statement in block)

### UnusedObject Rule

Checks for object allocations that are not assigned or used, unless it is the last statement within a block (because it may be the intentional return value). Examples include:

By default, this rule does not analyze test files. This rule sets the default value of the doNotApplyToFilesMatching property to ignore file names ending in 'Test.groovy', 'Tests.groovy' or 'TestCase.groovy'. Invoking constructors without using the result is a common pattern in tests.

        int myMethod() {
            new BigDecimal("23.45")     // unused
            return -1
        }

        BigDecimal myMethod() {
            new BigDecimal("23.45")     // OK (last statement in block)
        }

        def closure = {
            doStuff()
            new Date()                  // unused
            doOtherStuff()
        }

        def closure = { new Date() }    // OK (last statement in block)

### UnusedPrivateField Rule

Checks for private fields that are not referenced within the same class. Note that the `private` modifier is not currently "respected" by Groovy code (i.e., Groovy can access `private` members within other classes). By default, fields named `serialVersionUID` are ignored. The rule has a property named ignoreFieldNames, which can be set to ignore other field names as well. For instance, to ignore fields named 'fieldx', set the property to the 'fieldx, serialVersionUID'

Property | Description | Default Value
ignoreFieldNames | Specifies one or more (comma-separated) field names that should be ignored (i.e., that should not cause a rule violation). The names may optionally contain wildcards (*,?). | serialVersionUID

Known limitations:

- Does not recognize field access when field name is a GString (e.g. `this."$fieldName"`)
- Does not recognize access of private field of another instance (i.e. other than `this`)

### UnusedPrivateMethod Rule

Checks for private methods that are not referenced within the same class. Note that the `private` modifier is not currently "respected" by Groovy code (i.e., Groovy can access `private` members within other classes).

Known limitations:

- Does not recognize method reference through property access (e.g. `getName()` accessed as `x.name`)
- Does not recognize method invocations when method name is a GString (e.g. `this."$methodName"()`)
- Does not recognize invoking private method of another instance (i.e. other than `this`)
- Does not differentiate between multiple private methods with the same name but different parameters (i.e., overloaded)
- Does not check for unused constructors

### UnusedPrivateMethodParameter Rule

Since CodeNarc 0.12

Checks for parameters to private methods that are not referenced within the method body. Note that the `private` modifier is not currently "respected" by Groovy code (i.e., Groovy can access `private` members within other classes).

Known limitations:

- Does not recognize parameter references within an inner class. See CodeNarc bug #3155974.
- Does not recognize parameter references when parameter name is a GString (e.g. `println "$parameterName"`)

  Since CodeNarc 0.14 * You can specify an ignore list using the 'ignoreRegex' property. By default, a parameter named 'ignore' or 'ignored' does not trigger a violation (the regex value is 'ignore|ignored'). You can add your own ignore list using this property.

### UnusedMethodParameter Rule

New in CodeNarc 0.16

This rule finds instances of method parameters not being used. It does not analyze private methods (that is done by the UnusedPrivateMethodParameter rule) or methods marked @Override.

- This rule ignores `main()` methods. In Groovy, the `main()>> method can either specify a <<<void` return type or else omit a return type (be dynamically typed). The `main()>> method must have exactly one parameter. That parameter can either be typed as <<<String[]` or else the type can be omitted (be dynamically typed). And the `main()>> method must be <<<static`.
- You can specify an ignore list of parameter names using the 'ignoreRegex' property. By default, a parameter named 'ignore' or 'ignored' does not trigger a violation (the regex value is 'ignore|ignored'). You can add your own ignore list using this property.
- You can specify a class name pattern to ignore using the 'ignoreClassRegex' property. By default classes named '*.Category' are ignored because they are category classes and have unused parameters in static methods.

  Example of violations:

          class MyClass {
              def method(def param) {
                  // param is unused
              }
          }

  Example of code that does not cause violations:

          class MyClass {
              @Override
              def otherMethod(def param) {
                  // this is OK because it overrides a super class
              }
          }

          class MyCategory {
              // Category classes are ignored by default
              void myMethod1(String string, int value) { }
              void myMethod1(String string, int value, name) { }
          }

          class MainClass1 {
              // main() methods are ignored
              public static void main(String[] args) { }
          }
          class MainClass2 {
              // This is also a valid Groovy main() method
              static main(args) { }
          }

### UnusedVariable Rule

Checks for variables that are never referenced.

The rule has a property named ignoreVariableNames, which can be set to ignore some variable names. For instance, to ignore fields named 'unused', set the property to 'unused'.

Property | Description | Default Value
ignoreVariableNames | Specifies one or more (comma-separated) variable names that should be ignored (i.e., that should not cause a rule violation). The names may optionally contain wildcards (*,?). | `null`

Known limitations:

- Incorrectly considers a variable referenced if another variable with the same name is referenced elsewhere (in another scope/block).