Classes with Only Static Methods

Rule ID:

static_only_class

Severity:

high

Classes that consist only of static functions and declarations are hacked namespaces. They are bad practice and must not exist.

Scope and Exceptions

A class with a virtual destructor is a polymorphic interface, even if its remaining methods are static factories. The scanner does not report these classes. Derived classes are also excluded because their inherited non-static behavior may not be visible in the declaration.

Correct Solution

• A collection of free functions can be put into a regular header with proper unique naming in its namespace.

• If the functions all share an explicit domain that would make their names repetitive, putting all functions in this header into a special namespace such as erbsland::<domain>::impl::<special> can make sense. At the usage location, this namespace may be imported for more readable code.

• Usually, this is a symptom of bad design. Functions should be arranged around data. Data can be values the functions operate on or simply configuration. For example, free functions such as doSomething(config, value) could be arranged around config.

Mechanical Detection

The scanner reports namespace-scope classes with static members but no instance state or non-static behavior.