How Can We Create the Simplest and Most Robust C 11 ScopeGuard?

What is the Simplest and Neatest C 11 ScopeGuard?

Problem:

A developer seeks to simplify ScopeGuard, a technique used for handling resource acquisition and release in C . They're aiming for a version with minimal lines of code while addressing potential concerns.

Answer:

A succinctly designed ScopeGuard in C 11:

<code class="cpp">class scope_guard {
public:
    template<class Callable>
    scope_guard(Callable &&undo_func) try : f(std::forward<Callable>(undo_func)) {
    } catch(...) {
        undo_func();
        throw;
    }
    
    // ... (additional implementation omitted for brevity)
};</code>

Key Features:

• Utilizes lambda expressions for flexible cleanup actions.
• Adopts an exception-safe constructor to prevent leaks.
• Provides a dismiss() method to manually disable cleanup.

ScopeGuard Evolution:

The provided ScopeGuard has undergone refinement over time, incorporating improvements such as:

• Execution Policy: Allows finer control over cleanup execution based on exception status.
• Exception Safety: Ensures that the cleanup code does not throw exceptions, eliminating potential termination issues.

Usage:

<code class="cpp">scope_guard scope_exit, scope_fail(scope_guard::execution::exception);

// Acquire/release resources
scope_exit += [](){ cleanup1(); };
scope_fail += [](){ rollback1(); };</code>

Benefits:

• Simplicity: Offers a straightforward and concise implementation.
• Robustness: Handles exceptions gracefully and prevents resource leaks.
• Flexibility: Enables multiple cleanup actions and customizable execution policies.

Additional Notes:

• This ScopeGuard avoids templating the guard class to improve code readability.
• It follows the same principles as Alexandrescu's original concept while leveraging C 11 idioms for ease of use.

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