C++ Library Development

C++-specific patterns for library development. This skill extends meta-library-dev with C++ tooling, modern C++ idioms (C++17/20/23), and ecosystem practices.

This Skill Extends

• meta-library-dev - Foundational library patterns (API design, versioning, testing strategies)
• lang-cpp-dev - Core C++ language features and patterns

For general concepts like semantic versioning, module organization principles, and testing pyramids, see the meta-skill first.

This Skill Adds

• Library architecture: Header-only vs compiled libraries, template libraries
• CMake tooling: Library targets, installation, package configuration
• ABI stability: Version management, symbol visibility, compatibility
• Package managers: Conan, vcpkg integration
• Documentation: Doxygen patterns for libraries
• Testing: GoogleTest, Catch2 patterns for library testing

This Skill Does NOT Cover

• General library patterns - see meta-library-dev
• Core C++ syntax and features - see lang-cpp-dev
• CMake basics - see lang-cpp-cmake-dev
• Memory optimization - see lang-cpp-memory-eng
• Performance profiling - see lang-cpp-profiling-eng

---

Quick Reference

Task	Command/Pattern
CMake library target	add_library(mylib src/mylib.cpp)
Header-only library	add_library(mylib INTERFACE)
Build library	cmake --build build
Install library	cmake --install build
Run tests	ctest --test-dir build
Generate docs	doxygen Doxyfile
Conan install	conan install . --build=missing
vcpkg install	vcpkg install mylib

---

Library Architecture

Header-Only vs Compiled Libraries

Header-Only Libraries:

// my_library.hpp
#ifndef MY_LIBRARY_HPP
#define MY_LIBRARY_HPP

#include <string>
#include <vector>

namespace mylib {

// All code in headers - no .cpp files
template<typename T>
class Container {
public:
    void add(const T& item) {
        items_.push_back(item);
    }

    size_t size() const {
        return items_.size();
    }

private:
    std::vector<T> items_;
};

// Non-template functions must be inline
inline std::string version() {
    return "1.0.0";
}

} // namespace mylib

#endif

Compiled Libraries:

// include/mylib/mylib.hpp
#ifndef MYLIB_HPP
#define MYLIB_HPP

#include <string>
#include <memory>

namespace mylib {

class Parser {
public:
    Parser();
    ~Parser();

    // Public interface only
    bool parse(const std::string& input);
    std::string result() const;

private:
    struct Impl;  // PIMPL pattern
    std::unique_ptr<Impl> impl_;
};

} // namespace mylib

#endif

// src/mylib.cpp
#include "mylib/mylib.hpp"

namespace mylib {

struct Parser::Impl {
    std::string result;
    // Implementation details hidden
};

Parser::Parser() : impl_(std::make_unique<Impl>()) {}
Parser::~Parser() = default;

bool Parser::parse(const std::string& input) {
    // Implementation
    impl_->result = "parsed: " + input;
    return true;
}

std::string Parser::result() const {
    return impl_->result;
}

} // namespace mylib

When to Use Each

Pattern	Use When	Pros	Cons
Header-only	Templates, small utilities	No linking, easy distribution	Longer compile times, code bloat
Compiled	Large implementations, ABI stability	Fast compilation, smaller binaries	Requires linking, distribution complexity
Hybrid	Mix of both	Best of both worlds	More complex build setup

---

CMake Library Configuration

Basic Library Target

cmake_minimum_required(VERSION 3.15)
project(MyLibrary VERSION 1.0.0 LANGUAGES CXX)

# Set C++ standard
set(CMAKE_CXX_STANDARD 17)
set(CMAKE_CXX_STANDARD_REQUIRED ON)
set(CMAKE_CXX_EXTENSIONS OFF)

# Compiled library
add_library(mylib
    src/parser.cpp
    src/serializer.cpp
)

# Include directories
target_include_directories(mylib
    PUBLIC
        $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include>
        $<INSTALL_INTERFACE:include>
    PRIVATE
        ${CMAKE_CURRENT_SOURCE_DIR}/src
)

# Link dependencies
target_link_libraries(mylib
    PUBLIC
        fmt::fmt
    PRIVATE
        nlohmann_json::nlohmann_json
)

# Set library properties
set_target_properties(mylib PROPERTIES
    VERSION ${PROJECT_VERSION}
    SOVERSION ${PROJECT_VERSION_MAJOR}
    PUBLIC_HEADER include/mylib/mylib.hpp
)

Header-Only Library

# Interface library (header-only)
add_library(mylib INTERFACE)

target_include_directories(mylib
    INTERFACE
        $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/include>
        $<INSTALL_INTERFACE:include>
)

target_compile_features(mylib INTERFACE cxx_std_17)

# Header-only dependencies
target_link_libraries(mylib
    INTERFACE
        range-v3::range-v3
)

Static vs Shared Library

# Option for library type
option(BUILD_SHARED_LIBS "Build shared libraries" OFF)

add_library(mylib
    src/parser.cpp
    src/serializer.cpp
)

# Or explicitly
add_library(mylib_static STATIC src/parser.cpp)
add_library(mylib_shared SHARED src/parser.cpp)

# Symbol visibility for shared libraries
include(GenerateExportHeader)
generate_export_header(mylib
    EXPORT_FILE_NAME ${CMAKE_BINARY_DIR}/include/mylib/export.hpp
)

target_compile_definitions(mylib
    PRIVATE
        MYLIB_EXPORTS  # When building the library
)

Installation Configuration

include(GNUInstallDirs)
include(CMakePackageConfigHelpers)

# Install targets
install(TARGETS mylib
    EXPORT mylibTargets
    LIBRARY DESTINATION ${CMAKE_INSTALL_LIBDIR}
    ARCHIVE DESTINATION ${CMAKE_INSTALL_LIBDIR}
    RUNTIME DESTINATION ${CMAKE_INSTALL_BINDIR}
    PUBLIC_HEADER DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}/mylib
)

# Install headers
install(DIRECTORY include/
    DESTINATION ${CMAKE_INSTALL_INCLUDEDIR}
)

# Export targets
install(EXPORT mylibTargets
    FILE mylibTargets.cmake
    NAMESPACE mylib::
    DESTINATION ${CMAKE_INSTALL_LIBDIR}/cmake/mylib
)

# Generate package config
configure_package_config_file(
    ${CMAKE_CURRENT_SOURCE_DIR}/cmake/mylibConfig.cmake.in
    ${CMAKE_CURRENT_BINARY_DIR}/mylibConfig.cmake
    INSTALL_DESTINATION ${CMAKE_INSTALL_LIBDIR}/cmake/mylib
)

# Generate version file
write_basic_package_version_file(
    ${CMAKE_CURRENT_BINARY_DIR}/mylibConfigVersion.cmake
    VERSION ${PROJECT_VERSION}
    COMPATIBILITY SameMajorVersion
)

# Install package config files
install(FILES
    ${CMAKE_CURRENT_BINARY_DIR}/mylibConfig.cmake
    ${CMAKE_CURRENT_BINARY_DIR}/mylibConfigVersion.cmake
    DESTINATION ${CMAKE_INSTALL_LIBDIR}/cmake/mylib
)

Package Config Template

# cmake/mylibConfig.cmake.in
@PACKAGE_INIT@

include(CMakeFindDependencyMacro)

# Find dependencies
find_dependency(fmt)

# Include targets
include("${CMAKE_CURRENT_LIST_DIR}/mylibTargets.cmake")

check_required_components(mylib)

---

Symbol Visibility and ABI Stability

Export Macros

// include/mylib/export.hpp
#ifndef MYLIB_EXPORT_HPP
#define MYLIB_EXPORT_HPP

#ifdef _WIN32
    #ifdef MYLIB_EXPORTS
        #define MYLIB_API __declspec(dllexport)
    #else
        #define MYLIB_API __declspec(dllimport)
    #endif
#else
    #define MYLIB_API __attribute__((visibility("default")))
#endif

#endif

// Usage in headers
#include "mylib/export.hpp"

namespace mylib {

class MYLIB_API Parser {
public:
    Parser();
    ~Parser();
    bool parse(const std::string& input);
};

} // namespace mylib

CMake Visibility Configuration

# Set default symbol visibility to hidden
set_target_properties(mylib PROPERTIES
    CXX_VISIBILITY_PRESET hidden
    VISIBILITY_INLINES_HIDDEN ON
)

# Generate export header
include(GenerateExportHeader)
generate_export_header(mylib
    BASE_NAME MYLIB
    EXPORT_FILE_NAME ${CMAKE_BINARY_DIR}/include/mylib/export.hpp
)

ABI Versioning

// Use inline namespaces for ABI versioning
namespace mylib {
inline namespace v1 {

class Parser {
    // v1 implementation
};

} // namespace v1

// When breaking ABI in next major version:
// inline namespace v2 {
//     class Parser { /* new implementation */ };
// }

} // namespace mylib

// Users automatically get latest inline namespace
mylib::Parser p;  // Uses mylib::v1::Parser

PIMPL Pattern for ABI Stability

// Public header - ABI stable
// include/mylib/database.hpp
#ifndef MYLIB_DATABASE_HPP
#define MYLIB_DATABASE_HPP

#include <memory>
#include <string>

namespace mylib {

class Database {
public:
    Database(const std::string& path);
    ~Database();

    // Copyable/movable
    Database(const Database&);
    Database& operator=(const Database&);
    Database(Database&&) noexcept;
    Database& operator=(Database&&) noexcept;

    void execute(const std::string& query);

private:
    struct Impl;
    std::unique_ptr<Impl> impl_;
};

} // namespace mylib

#endif

// Implementation - can change without breaking ABI
// src/database.cpp
#include "mylib/database.hpp"
#include <vector>
#include <map>

namespace mylib {

struct Database::Impl {
    std::string path;
    std::vector<std::string> cache;
    std::map<std::string, int> indices;

    // Private implementation details
};

Database::Database(const std::string& path)
    : impl_(std::make_unique<Impl>()) {
    impl_->path = path;
}

Database::~Database() = default;

Database::Database(const Database& other)
    : impl_(std::make_unique<Impl>(*other.impl_)) {}

Database& Database::operator=(const Database& other) {
    if (this != &other) {
        impl_ = std::make_unique<Impl>(*other.impl_);
    }
    return *this;
}

Database::Database(Database&&) noexcept = default;
Database& Database::operator=(Database&&) noexcept = default;

void Database::execute(const std::string& query) {
    // Implementation
}

} // namespace mylib

---

Template Library Patterns

Header Organization

include/
└── mylib/
    ├── mylib.hpp           # Main public header
    ├── container.hpp       # Template class
    └── detail/
        └── impl.hpp        # Implementation details

// include/mylib/container.hpp
#ifndef MYLIB_CONTAINER_HPP
#define MYLIB_CONTAINER_HPP

#include <vector>
#include <algorithm>

namespace mylib {

template<typename T>
class Container {
public:
    void add(const T& item);
    void add(T&& item);

    template<typename Predicate>
    void remove_if(Predicate pred);

    size_t size() const { return items_.size(); }

private:
    std::vector<T> items_;
};

// Template implementations in same header
template<typename T>
void Container<T>::add(const T& item) {
    items_.push_back(item);
}

template<typename T>
void Container<T>::add(T&& item) {
    items_.push_back(std::move(item));
}

template<typename T>
template<typename Predicate>
void Container<T>::remove_if(Predicate pred) {
    items_.erase(
        std::remove_if(items_.begin(), items_.end(), pred),
        items_.end()
    );
}

} // namespace mylib

#endif

Extern Templates (Reduce Compile Time)

// mylib.hpp - Declaration
template<typename T>
class Container {
    void add(const T& item);
};

// mylib_extern.hpp - Extern template declarations
extern template class Container<int>;
extern template class Container<std::string>;

// mylib.cpp - Explicit instantiation
#include "mylib.hpp"

template class Container<int>;
template class Container<std::string>;

Concepts for Template Constraints (C++20)

#include <concepts>

namespace mylib {

// Define concepts
template<typename T>
concept Serializable = requires(T t) {
    { t.serialize() } -> std::convertible_to<std::string>;
};

template<typename T>
concept Numeric = std::is_arithmetic_v<T>;

// Use in templates
template<Serializable T>
class DataStore {
public:
    void save(const T& data) {
        std::string serialized = data.serialize();
        // Save serialized data
    }
};

// Multiple constraints
template<typename T>
concept Container = requires(T t) {
    typename T::value_type;
    { t.size() } -> std::convertible_to<size_t>;
    { t.begin() } -> std::input_iterator;
    { t.end() } -> std::input_iterator;
};

template<Container C>
void process(const C& container) {
    for (const auto& item : container) {
        // Process item
    }
}

} // namespace mylib

---

Package Manager Integration

Conan Configuration

# conanfile.py
from conan import ConanFile
from conan.tools.cmake import CMakeToolchain, CMake, cmake_layout

class MyLibConan(ConanFile):
    name = "mylib"
    version = "1.0.0"
    license = "MIT"
    author = "Your Name <your.email@example.com>"
    url = "https://github.com/username/mylib"
    description = "A C++ library for parsing"
    topics = ("parsing", "cpp", "library")
    settings = "os", "compiler", "build_type", "arch"
    options = {
        "shared": [True, False],
        "fPIC": [True, False]
    }
    default_options = {
        "shared": False,
        "fPIC": True
    }
    exports_sources = "CMakeLists.txt", "src/*", "include/*"

    def requirements(self):
        self.requires("fmt/9.1.0")
        self.requires("nlohmann_json/3.11.2")

    def config_options(self):
        if self.settings.os == "Windows":
            del self.options.fPIC

    def layout(self):
        cmake_layout(self)

    def generate(self):
        tc = CMakeToolchain(self)
        tc.generate()

    def build(self):
        cmake = CMake(self)
        cmake.configure()
        cmake.build()

    def package(self):
        cmake = CMake(self)
        cmake.install()

    def package_info(self):
        self.cpp_info.libs = ["mylib"]
        self.cpp_info.includedirs = ["include"]

vcpkg Configuration

{
  "name": "mylib",
  "version": "1.0.0",
  "description": "A C++ library for parsing",
  "homepage": "https://github.com/username/mylib",
  "license": "MIT",
  "dependencies": [
    "fmt",
    "nlohmann-json"
  ],
  "features": {
    "tests": {
      "description": "Build tests",
      "dependencies": [
        "gtest"
      ]
    }
  }
}

# ports/mylib/portfile.cmake
vcpkg_from_github(
    OUT_SOURCE_PATH SOURCE_PATH
    REPO username/mylib
    REF v1.0.0
    SHA512 <hash>
    HEAD_REF main
)

vcpkg_cmake_configure(
    SOURCE_PATH "${SOURCE_PATH}"
    OPTIONS
        -DBUILD_TESTING=OFF
)

vcpkg_cmake_install()
vcpkg_cmake_config_fixup(CONFIG_PATH lib/cmake/mylib)

file(REMOVE_RECURSE "${CURRENT_PACKAGES_DIR}/debug/include")
file(INSTALL "${SOURCE_PATH}/LICENSE" DESTINATION "${CURRENT_PACKAGES_DIR}/share/${PORT}" RENAME copyright)

---

Documentation with Doxygen

Doxyfile Configuration

# Doxyfile
PROJECT_NAME           = "MyLib"
PROJECT_BRIEF          = "A modern C++ parsing library"
PROJECT_VERSION        = 1.0.0

INPUT                  = include/ src/ README.md
FILE_PATTERNS          = *.hpp *.cpp *.md
RECURSIVE              = YES
EXCLUDE_PATTERNS       = */detail/* */test/*

EXTRACT_ALL            = YES
EXTRACT_PRIVATE        = NO
EXTRACT_STATIC         = YES

GENERATE_HTML          = YES
HTML_OUTPUT            = docs/html
GENERATE_LATEX         = NO

USE_MDFILE_AS_MAINPAGE = README.md
MARKDOWN_SUPPORT       = YES

ENABLE_PREPROCESSING   = YES
MACRO_EXPANSION        = YES
EXPAND_ONLY_PREDEF     = NO

HAVE_DOT               = YES
CALL_GRAPH             = YES
CALLER_GRAPH           = YES
CLASS_DIAGRAMS         = YES

Documentation Comments

/**
 * @file parser.hpp
 * @brief Main parser interface
 * @author Your Name
 * @version 1.0.0
 */

#ifndef MYLIB_PARSER_HPP
#define MYLIB_PARSER_HPP

namespace mylib {

/**
 * @brief A parser for processing input data
 *
 * This class provides methods for parsing various input formats
 * and converting them to structured data.
 *
 * @code
 * Parser p;
 * p.parse("input data");
 * auto result = p.result();
 * @endcode
 *
 * @note The parser is not thread-safe
 * @warning Reusing the same parser instance may lead to data races
 */
class Parser {
public:
    /**
     * @brief Construct a new Parser object
     *
     * @param strict Enable strict parsing mode
     * @throw std::invalid_argument if configuration is invalid
     */
    explicit Parser(bool strict = false);

    /**
     * @brief Parse input data
     *
     * @param input The input string to parse
     * @return true if parsing succeeded
     * @return false if parsing failed
     *
     * @pre input must not be empty
     * @post result() contains parsed data if successful
     *
     * @see result()
     */
    bool parse(const std::string& input);

    /**
     * @brief Get the parsing result
     *
     * @return const std::string& Reference to the result
     *
     * @pre parse() must have been called successfully
     */
    const std::string& result() const;

private:
    bool strict_;         ///< Strict parsing mode flag
    std::string result_;  ///< Parsed result storage
};

/**
 * @brief Parse input with default settings
 *
 * @tparam T The output type
 * @param input Input string
 * @return T Parsed result
 *
 * @example
 * @code
 * auto data = parse<Data>("input");
 * @endcode
 */
template<typename T>
T parse(const std::string& input);

} // namespace mylib

#endif

CMake Integration

# Find Doxygen
find_package(Doxygen)

if(DOXYGEN_FOUND)
    # Configure Doxyfile
    set(DOXYGEN_IN ${CMAKE_CURRENT_SOURCE_DIR}/docs/Doxyfile.in)
    set(DOXYGEN_OUT ${CMAKE_CURRENT_BINARY_DIR}/Doxyfile)

    configure_file(${DOXYGEN_IN} ${DOXYGEN_OUT} @ONLY)

    # Add documentation target
    add_custom_target(docs
        COMMAND ${DOXYGEN_EXECUTABLE} ${DOXYGEN_OUT}
        WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}
        COMMENT "Generating API documentation with Doxygen"
        VERBATIM
    )
endif()

---

Testing with GoogleTest

CMake Test Configuration

# Enable testing
enable_testing()

# Find GoogleTest
find_package(GTest REQUIRED)

# Test executable
add_executable(mylib_test
    tests/parser_test.cpp
    tests/serializer_test.cpp
)

target_link_libraries(mylib_test
    PRIVATE
        mylib
        GTest::gtest
        GTest::gtest_main
)

# Discover tests
include(GoogleTest)
gtest_discover_tests(mylib_test)

Test Structure

// tests/parser_test.cpp
#include <gtest/gtest.h>
#include "mylib/parser.hpp"

namespace mylib {
namespace test {

class ParserTest : public ::testing::Test {
protected:
    void SetUp() override {
        parser = std::make_unique<Parser>();
    }

    void TearDown() override {
        parser.reset();
    }

    std::unique_ptr<Parser> parser;
};

TEST_F(ParserTest, ParseValidInput) {
    ASSERT_TRUE(parser->parse("valid input"));
    EXPECT_EQ(parser->result(), "parsed: valid input");
}

TEST_F(ParserTest, ParseEmptyInput) {
    EXPECT_FALSE(parser->parse(""));
}

TEST_F(ParserTest, ParseWithStrictMode) {
    Parser strict_parser(true);
    EXPECT_THROW(strict_parser.parse("invalid"), std::runtime_error);
}

// Parameterized tests
class ParserParamTest : public ::testing::TestWithParam<std::string> {};

TEST_P(ParserParamTest, ParseMultipleInputs) {
    Parser p;
    EXPECT_TRUE(p.parse(GetParam()));
}

INSTANTIATE_TEST_SUITE_P(
    ValidInputs,
    ParserParamTest,
    ::testing::Values("input1", "input2", "input3")
);

} // namespace test
} // namespace mylib

---

Testing with Catch2

CMake Configuration

find_package(Catch2 3 REQUIRED)

add_executable(mylib_test
    tests/parser_test.cpp
)

target_link_libraries(mylib_test
    PRIVATE
        mylib
        Catch2::Catch2WithMain
)

include(Catch)
catch_discover_tests(mylib_test)

Test Structure

// tests/parser_test.cpp
#include <catch2/catch_test_macros.hpp>
#include "mylib/parser.hpp"

TEST_CASE("Parser handles valid input", "[parser]") {
    mylib::Parser p;

    SECTION("Basic parsing") {
        REQUIRE(p.parse("test input"));
        REQUIRE(p.result() == "parsed: test input");
    }

    SECTION("Empty input fails") {
        REQUIRE_FALSE(p.parse(""));
    }
}

TEST_CASE("Parser with strict mode", "[parser][strict]") {
    mylib::Parser p(true);

    REQUIRE_THROWS_AS(p.parse("invalid"), std::runtime_error);
}

// Template tests
TEMPLATE_TEST_CASE("Container works with different types",
                   "[container][template]",
                   int, double, std::string) {
    mylib::Container<TestType> container;

    TestType value{};
    container.add(value);

    REQUIRE(container.size() == 1);
}

---

Versioning Best Practices

Semantic Versioning

MAJOR.MINOR.PATCH (e.g., 1.2.3)

MAJOR: Incompatible API changes (breaking changes)
MINOR: Backward-compatible functionality additions
PATCH: Backward-compatible bug fixes

Version Header

// include/mylib/version.hpp
#ifndef MYLIB_VERSION_HPP
#define MYLIB_VERSION_HPP

#define MYLIB_VERSION_MAJOR 1
#define MYLIB_VERSION_MINOR 0
#define MYLIB_VERSION_PATCH 0

#define MYLIB_VERSION \
    (MYLIB_VERSION_MAJOR * 10000 + \
     MYLIB_VERSION_MINOR * 100 + \
     MYLIB_VERSION_PATCH)

#define MYLIB_VERSION_STRING "1.0.0"

namespace mylib {

struct Version {
    static constexpr int major = MYLIB_VERSION_MAJOR;
    static constexpr int minor = MYLIB_VERSION_MINOR;
    static constexpr int patch = MYLIB_VERSION_PATCH;
    static constexpr const char* string = MYLIB_VERSION_STRING;
};

} // namespace mylib

#endif

CMake Version Configuration

# CMakeLists.txt
project(MyLib VERSION 1.0.0)

# Generate version header
configure_file(
    ${CMAKE_CURRENT_SOURCE_DIR}/include/mylib/version.hpp.in
    ${CMAKE_CURRENT_BINARY_DIR}/include/mylib/version.hpp
)

// include/mylib/version.hpp.in
#ifndef MYLIB_VERSION_HPP
#define MYLIB_VERSION_HPP

#define MYLIB_VERSION_MAJOR @PROJECT_VERSION_MAJOR@
#define MYLIB_VERSION_MINOR @PROJECT_VERSION_MINOR@
#define MYLIB_VERSION_PATCH @PROJECT_VERSION_PATCH@

#define MYLIB_VERSION_STRING "@PROJECT_VERSION@"

#endif

---

Example: Complete Library Structure

mylib/
├── CMakeLists.txt
├── conanfile.py
├── vcpkg.json
├── README.md
├── LICENSE
├── CHANGELOG.md
├── Doxyfile
├── .clang-format
├── include/
│   └── mylib/
│       ├── mylib.hpp          # Main public header
│       ├── parser.hpp
│       ├── serializer.hpp
│       ├── version.hpp
│       └── export.hpp
├── src/
│   ├── parser.cpp
│   └── serializer.cpp
├── tests/
│   ├── CMakeLists.txt
│   ├── parser_test.cpp
│   └── serializer_test.cpp
├── examples/
│   ├── CMakeLists.txt
│   ├── basic_usage.cpp
│   └── advanced_usage.cpp
├── docs/
│   └── Doxyfile.in
└── cmake/
    ├── mylibConfig.cmake.in
    └── FindMyLibDeps.cmake

---

Anti-Patterns

1. Exposing Implementation Details

// Bad: Exposing internal types
class Parser {
public:
    std::shared_ptr<InternalNode> parse(const std::string& input);
};

// Good: Return opaque type or public interface
class Parser {
public:
    Document parse(const std::string& input);
};

2. Using using namespace in Headers

// Bad: Pollutes namespace for users
// mylib.hpp
using namespace std;

class Parser {
    string parse(const string& input);
};

// Good: Fully qualified names
// mylib.hpp
class Parser {
    std::string parse(const std::string& input);
};

3. Inline Everything

// Bad: Large inline functions
class Parser {
    void parse(const std::string& input) {
        // 100 lines of code...
    }
};

// Good: Separate declaration and definition
class Parser {
    void parse(const std::string& input);
};

4. Breaking ABI Without Major Version Bump

// v1.0.0
class Data {
    int value;
};

// v1.1.0 - WRONG! This breaks ABI
class Data {
    int value;
    int newValue;  // Changes size/layout
};

// Correct: Create new type or bump major version

---

References

• meta-library-dev - Foundational library patterns
• lang-cpp-dev - Core C++ features
• lang-cpp-cmake-dev - CMake configuration
• CMake Documentation
• Conan Documentation
• vcpkg Documentation
• GoogleTest Documentation
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