feature_flags_example.cpp

Demonstrates compile-time feature detection and conditional compilation with feature flags.

Demonstrates compile-time feature detection and conditional compilation with feature flags.Shows how to query compiler capabilities, C++ standard library features, and ecosystem system availability at compile time.

See also

kcenon/common/config/feature_flags.h

// BSD 3-Clause License
// Copyright (c) 2021-2025, 🍀☀🌕🌥 🌊
// See the LICENSE file in the project root for full license information.
 
 
#include <kcenon/common/config/feature_flags.h>
 
#include <iostream>
#include <string>
 
#if KCENON_HAS_SOURCE_LOCATION
#include <source_location>
#endif
 
// Helper to convert bool to string
constexpr const char* yes_no(bool v) { return v ? "yes" : "no"; }
 
int main()
{
    std::cout << "=== Feature Flags Example ===\n\n";
 
    // 1. C++ Standard Library Features
    std::cout << "1. C++ Standard Library Features:\n";
 
#if KCENON_HAS_SOURCE_LOCATION
    std::cout << "   std::source_location: supported\n";
#else
    std::cout << "   std::source_location: not supported (using polyfill)\n";
#endif
 
#if KCENON_HAS_JTHREAD
    std::cout << "   std::jthread: supported\n";
#else
    std::cout << "   std::jthread: not supported\n";
#endif
 
#ifdef __cpp_concepts
    std::cout << "   C++20 concepts: supported (__cpp_concepts=" << __cpp_concepts << ")\n";
#else
    std::cout << "   C++20 concepts: not supported\n";
#endif
 
#ifdef __cpp_lib_format
    std::cout << "   std::format: supported\n";
#else
    std::cout << "   std::format: not supported\n";
#endif
 
    // 2. Ecosystem System Dependencies
    std::cout << "\n2. Ecosystem System Dependencies:\n";
 
#if KCENON_WITH_THREAD_SYSTEM
    std::cout << "   thread_system: linked\n";
#else
    std::cout << "   thread_system: not linked\n";
#endif
 
#if KCENON_WITH_LOGGER_SYSTEM
    std::cout << "   logger_system: linked\n";
#else
    std::cout << "   logger_system: not linked\n";
#endif
 
#if KCENON_WITH_MONITORING_SYSTEM
    std::cout << "   monitoring_system: linked\n";
#else
    std::cout << "   monitoring_system: not linked\n";
#endif
 
#if KCENON_WITH_CONTAINER_SYSTEM
    std::cout << "   container_system: linked\n";
#else
    std::cout << "   container_system: not linked\n";
#endif
 
    // 3. Conditional compilation example
    std::cout << "\n3. Conditional compilation patterns:\n";
 
#if KCENON_HAS_SOURCE_LOCATION
    auto loc = std::source_location::current();
    std::cout << "   Called from: " << loc.file_name() << ":" << loc.line() << "\n";
#else
    std::cout << "   Source location: using fallback (__FILE__:__LINE__)\n";
    std::cout << "   Called from: " << __FILE__ << ":" << __LINE__ << "\n";
#endif
 
    // 4. Platform detection
    std::cout << "\n4. Platform:\n";
#if defined(_WIN32) || defined(_WIN64)
    std::cout << "   OS: Windows\n";
#elif defined(__APPLE__)
    std::cout << "   OS: macOS\n";
#elif defined(__linux__)
    std::cout << "   OS: Linux\n";
#else
    std::cout << "   OS: Unknown\n";
#endif
 
    std::cout << "\nDone.\n";
    return 0;
}