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

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

TooManyPublicMethods

Since: 0.1

A class with too many public methods is probably a good suspect for refactoring, in order to reduce its complexity and find a way to have more fine grained objects.

By default it ignores methods starting with 'get' or 'set'.

Example

Source https://phpmd.org/rules/codesize.html#toomanypublicmethods

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

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

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

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

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

NPathComplexity

Since: 0.1

The NPath complexity of a method is the number of acyclic execution paths through that method. A threshold of 200 is generally considered the point where measures should be taken to reduce complexity.

Example

class Foo {
    function bar() {
        // lots of complicated code
    }
}

Source https://phpmd.org/rules/codesize.html#npathcomplexity

CyclomaticComplexity

Since: 0.1

Complexity is determined by the number of decision points in a method plus one for the method entry. The decision points are 'if', 'while', 'for', and 'case labels'. Generally, 1-4 is low complexity, 5-7 indicates moderate complexity, 8-10 is high complexity, and 11+ is very high complexity.

Example

// Cyclomatic Complexity = 11
class Foo {
1   public function example() {
2       if ($a == $b) {
3           if ($a1 == $b1) {
                fiddle();
4           } elseif ($a2 == $b2) {
                fiddle();
            } else {
                fiddle();
            }
5       } elseif ($c == $d) {
6           while ($c == $d) {
                fiddle();
            }
7        } elseif ($e == $f) {
8           for ($n = 0; $n < $h; $n++) {
                fiddle();
            }
        } else {
            switch ($z) {
9               case 1:
                    fiddle();
                    break;
10              case 2:
                    fiddle();
                    break;
11              case 3:
                    fiddle();
                    break;
                default:
                    fiddle();
                    break;
            }
        }
    }
}

Source https://phpmd.org/rules/codesize.html#cyclomaticcomplexity

CyclomaticComplexity

Since: 0.1

Complexity is determined by the number of decision points in a method plus one for the method entry. The decision points are 'if', 'while', 'for', and 'case labels'. Generally, 1-4 is low complexity, 5-7 indicates moderate complexity, 8-10 is high complexity, and 11+ is very high complexity.

Example

// Cyclomatic Complexity = 11
class Foo {
1   public function example() {
2       if ($a == $b) {
3           if ($a1 == $b1) {
                fiddle();
4           } elseif ($a2 == $b2) {
                fiddle();
            } else {
                fiddle();
            }
5       } elseif ($c == $d) {
6           while ($c == $d) {
                fiddle();
            }
7        } elseif ($e == $f) {
8           for ($n = 0; $n < $h; $n++) {
                fiddle();
            }
        } else {
            switch ($z) {
9               case 1:
                    fiddle();
                    break;
10              case 2:
                    fiddle();
                    break;
11              case 3:
                    fiddle();
                    break;
                default:
                    fiddle();
                    break;
            }
        }
    }
}

Source https://phpmd.org/rules/codesize.html#cyclomaticcomplexity

CouplingBetweenObjects

Since: 1.1.0

A class with too many dependencies has negative impacts on several quality aspects of a class. This includes quality criteria like stability, maintainability and understandability

Example

class Foo {
    /**
     * @var \foo\bar\X
     */
    private $x = null;

    /**
     * @var \foo\bar\Y
     */
    private $y = null;

    /**
     * @var \foo\bar\Z
     */
    private $z = null;

    public function setFoo(\Foo $foo) {}
    public function setBar(\Bar $bar) {}
    public function setBaz(\Baz $baz) {}

    /**
     * @return \SplObjectStorage
     * @throws \OutOfRangeException
     * @throws \InvalidArgumentException
     * @throws \ErrorException
     */
    public function process(\Iterator $it) {}

    // ...
}

Source https://phpmd.org/rules/design.html#couplingbetweenobjects

EmptyCatchBlock

Since: 2.7.0

Usually empty try-catch is a bad idea because you are silently swallowing an error condition and then continuing execution. Occasionally this may be the right thing to do, but often it's a sign that a developer saw an exception, didn't know what to do about it, and so used an empty catch to silence the problem.

Example

class Foo {

  public function bar()
  {
      try {
          // ...
      } catch (Exception $e) {} // empty catch block
  }
}

Source https://phpmd.org/rules/design.html#emptycatchblock

ShortVariable

Since: 0.2

Detects when a field, local, or parameter has a very short name.

Example

class Something {
    private $q = 15; // VIOLATION - Field
    public static function main( array $as ) { // VIOLATION - Formal
        $r = 20 + $this->q; // VIOLATION - Local
        for (int $i = 0; $i < 10; $i++) { // Not a Violation (inside FOR)
            $r += $this->q;
        }
    }
}

Source https://phpmd.org/rules/naming.html#shortvariable