Cognitive Complexity

Cognitive Complexity is a measure of how difficult a unit of code is to intuitively understand. Unlike Cyclomatic Complexity, which determines how difficult your code will be to test, Cognitive Complexity tells you how difficult your code will be to read and comprehend.

A method's cognitive complexity is based on a few simple rules:

• Code is not considered more complex when it uses shorthand that the language provides for collapsing multiple statements into one
• Code is considered more complex for each "break in the linear flow of the code"
• Code is considered more complex when "flow breaking structures are nested"

Further reading

• Cognitive Complexity docs
• Cognitive Complexity: A new way of measuring understandability

UnusedFormalParameter

Since: 0.2

Avoid passing parameters to methods or constructors and then not using those parameters.

Example

class Foo
{
    private function bar($howdy)
    {
        // $howdy is not used
    }
}

Source https://phpmd.org/rules/unusedcode.html#unusedformalparameter

CamelCasePropertyName

Since: 0.2

It is considered best practice to use the camelCase notation to name attributes.

Example

class ClassName {
    protected $property_name;
}

Source

CamelCaseMethodName

Since: 0.2

It is considered best practice to use the camelCase notation to name methods.

Example

class ClassName {
    public function get_name() {
    }
}

Source