PHPMD - PHP Mess Detector


Clean Code Rules

The Clean Code ruleset contains rules that enforce a clean code base. This includes rules from SOLID and object calisthenics.

BooleanArgumentFlag

Since: PHPMD 1.4.0

A boolean flag argument is a reliable indicator for a violation of the Single Responsibility Principle (SRP). You can fix this problem by extracting the logic in the boolean flag into its own class or method.

Example: :

class Foo {
    public function bar($flag = true) {
    }
}

ElseExpression

Since: PHPMD 1.4.0

An if expression with an else branch is basically not necessary. You can rewrite the conditions in a way that the else clause is not necessary and the code becomes simpler to read. To achieve this, use early return statements, though you may need to split the code in several smaller methods. For very simple assignments you could also use the ternary operations.

Example: :

class Foo
{
    public function bar($flag)
    {
        if ($flag) {
            // one branch
        } else {
            // another branch
        }
    }
}

StaticAccess

Since: PHPMD 1.4.0

Static access causes unexchangeable dependencies to other classes and leads to hard to test code. Avoid using static access at all costs and instead inject dependencies through the constructor. The only case when static access is acceptable is when used for factory methods.

Example: :

class Foo
{
    public function bar()
    {
        Bar::baz();
    }
}

This rule has the following properties:

NameDefault ValueDescription
exceptionsComma-separated class name list of exceptions

IfStatementAssignment

Since: PHPMD 2.7.0

Assignments in if clauses and the like are considered a code smell. Assignments in PHP return the right operand as their result. In many cases, this is an expected behavior, but can lead to many difficult to spot bugs, especially when the right operand could result in zero, null or an empty string.

Example: :

class Foo
{
    public function bar($flag)
    {
        if ($foo = 'bar') { // possible typo
            // ...
        }
        if ($baz = 0) { // always false
            // ...
        }
    }
}

DuplicatedArrayKey

Since: PHPMD 2.7.0

Defining another value for the same key in an array literal overrides the previous key/value, which makes it effectively an unused code. If it's known from the beginning that the key will have different value, there is usually no point in defining first one.

Example: :

function createArray() {
    return [
        'non-associative 0-element', // not applied
        0 => 'associative 0-element', // applied
        false => 'associative 0-element', // applied
        'foo' => 'bar', // not applied
        "foo" => 'baz', // applied
    ];
}

MissingImport

Since: PHPMD 2.7.0

Importing all external classes in a file through use statements makes them clearly visible.

Example: :

function make() {
    return new \stdClass();
}

Remark

This document is based on a ruleset xml-file, that was taken from the original source of the PMD project. This means that most parts of the content on this page are the intellectual work of the PMD community and its contributors and not of the PHPMD project.