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

StaticAccess

Since: 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();
    }
}

Source https://phpmd.org/rules/cleancode.html#staticaccess

StaticAccess

Since: 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();
    }
}

Source https://phpmd.org/rules/cleancode.html#staticaccess

StaticAccess

Since: 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();
    }
}

Source https://phpmd.org/rules/cleancode.html#staticaccess

StaticAccess

Since: 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();
    }
}

Source https://phpmd.org/rules/cleancode.html#staticaccess

StaticAccess

Since: 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();
    }
}

Source https://phpmd.org/rules/cleancode.html#staticaccess

StaticAccess

Since: 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();
    }
}

Source https://phpmd.org/rules/cleancode.html#staticaccess

StaticAccess

Since: 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();
    }
}

Source https://phpmd.org/rules/cleancode.html#staticaccess

StaticAccess

Since: 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();
    }
}

Source https://phpmd.org/rules/cleancode.html#staticaccess

StaticAccess

Since: 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();
    }
}

Source https://phpmd.org/rules/cleancode.html#staticaccess

StaticAccess

Since: 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();
    }
}

Source https://phpmd.org/rules/cleancode.html#staticaccess

StaticAccess

Since: 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();
    }
}

Source https://phpmd.org/rules/cleancode.html#staticaccess

Duplicated string literals make the process of refactoring error-prone, since you must be sure to update all occurrences.

On the other hand, constants can be referenced from many places, but only need to be updated in a single place.

Noncompliant Code Example

With the default threshold of 3:

function run() {
  prepare('action1');                              // Non-Compliant - 'action1' is duplicated 3 times
  execute('action1');
  release('action1');
}

Compliant Solution

ACTION_1 = 'action1';

function run() {
  prepare(ACTION_1);
  execute(ACTION_1);
  release(ACTION_1);
}

Exceptions

To prevent generating some false-positives, literals having less than 5 characters are excluded.

Shadowing fields with a local variable is a bad practice that reduces code readability: it makes it confusing to know whether the field or the variable is being used.

Noncompliant Code Example

class Foo {
  public $myField;

  public function doSomething() {
    $myField = 0;
    ...
  }
}

See

• CERT, DCL51-J. - Do not shadow or obscure identifiers in subscopes

Shadowing fields with a local variable is a bad practice that reduces code readability: it makes it confusing to know whether the field or the variable is being used.

Noncompliant Code Example

class Foo {
  public $myField;

  public function doSomething() {
    $myField = 0;
    ...
  }
}

See

• CERT, DCL51-J. - Do not shadow or obscure identifiers in subscopes

Shadowing fields with a local variable is a bad practice that reduces code readability: it makes it confusing to know whether the field or the variable is being used.

Noncompliant Code Example

class Foo {
  public $myField;

  public function doSomething() {
    $myField = 0;
    ...
  }
}

See

• CERT, DCL51-J. - Do not shadow or obscure identifiers in subscopes

Duplicated string literals make the process of refactoring error-prone, since you must be sure to update all occurrences.

On the other hand, constants can be referenced from many places, but only need to be updated in a single place.

Noncompliant Code Example

With the default threshold of 3:

function run() {
  prepare('action1');                              // Non-Compliant - 'action1' is duplicated 3 times
  execute('action1');
  release('action1');
}

Compliant Solution

ACTION_1 = 'action1';

function run() {
  prepare(ACTION_1);
  execute(ACTION_1);
  release(ACTION_1);
}

Exceptions

To prevent generating some false-positives, literals having less than 5 characters are excluded.

Duplicated string literals make the process of refactoring error-prone, since you must be sure to update all occurrences.

On the other hand, constants can be referenced from many places, but only need to be updated in a single place.

Noncompliant Code Example

With the default threshold of 3:

function run() {
  prepare('action1');                              // Non-Compliant - 'action1' is duplicated 3 times
  execute('action1');
  release('action1');
}

Compliant Solution

ACTION_1 = 'action1';

function run() {
  prepare(ACTION_1);
  execute(ACTION_1);
  release(ACTION_1);
}

Exceptions

To prevent generating some false-positives, literals having less than 5 characters are excluded.

UnusedLocalVariable

Since: 0.2

Detects when a local variable is declared and/or assigned, but not used.

Example

class Foo {
    public function doSomething()
    {
        $i = 5; // Unused
    }
}

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

CamelCaseVariableName

Since: 0.2

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

Example

class ClassName {
    public function doSomething() {
        $data_module = new DataModule();
    }
}

Source

CamelCaseVariableName

Since: 0.2

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

Example

class ClassName {
    public function doSomething() {
        $data_module = new DataModule();
    }
}

Source

CamelCaseVariableName

Since: 0.2

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

Example

class ClassName {
    public function doSomething() {
        $data_module = new DataModule();
    }
}

Source

CamelCaseVariableName

Since: 0.2

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

Example

class ClassName {
    public function doSomething() {
        $data_module = new DataModule();
    }
}

Source

CamelCaseVariableName

Since: 0.2

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

Example

class ClassName {
    public function doSomething() {
        $data_module = new DataModule();
    }
}

Source

CamelCaseVariableName

Since: 0.2

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

Example

class ClassName {
    public function doSomething() {
        $data_module = new DataModule();
    }
}

Source

CamelCaseVariableName

Since: 0.2

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

Example

class ClassName {
    public function doSomething() {
        $data_module = new DataModule();
    }
}

Source

CamelCaseVariableName

Since: 0.2

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

Example

class ClassName {
    public function doSomething() {
        $data_module = new DataModule();
    }
}

Source

CamelCaseVariableName

Since: 0.2

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

Example

class ClassName {
    public function doSomething() {
        $data_module = new DataModule();
    }
}

Source