functionStatic

Message: The member function 'x' can be static

Category: Readability

Severity: Style

Language: C++

Description

This checker identifies member functions that do not access any non-static member variables or call any non-static member functions. Such functions can be declared as static to indicate that they don't require an object instance to operate.

This warning helps improve code quality by:

• Making the function's independence from object state explicit
• Enabling the function to be called without creating an object instance
• Clarifying the function's scope and dependencies

Motivation

The motivation of this checker is to improve readability.

How to fix

Add the static keyword to the function declaration to indicate that it doesn't require an object instance.

Before:

class Calculator {
public:
    int add(int a, int b) {
        return a + b;  // Only uses parameters
    }

    void printMessage() {
        std::cout << "Hello World" << std::endl;  // Uses no instance data
    }

    bool isValidNumber(int num) {
        return num > 0 && num < 1000;  // Pure function
    }
};

After:

class Calculator {
public:
    static int add(int a, int b) {
        return a + b;  // Can be called as Calculator::add(5, 3)
    }

    static void printMessage() {
        std::cout << "Hello World" << std::endl;  // Can be called without instance
    }

    static bool isValidNumber(int num) {
        return num > 0 && num < 1000;  // Clearly indicates no state dependency
    }
};

Related checkers

• functionConst - for member functions that can be declared const