Reworked the examples.

.clang-format

@@ -1,12 +1,12 @@
 ---
-Language:        Cpp
+Language: Cpp
 # BasedOnStyle:  LLVM
 AccessModifierOffset: -4
 AlignAfterOpenBracket: Align
 AlignConsecutiveAssignments: false
 AlignConsecutiveDeclarations: false
 AlignEscapedNewlines: Right
-AlignOperands:   true
+AlignOperands: true
 AlignTrailingComments: true
 AllowAllParametersOfDeclarationOnNextLine: true
 AllowShortBlocksOnASingleLine: false
@@ -21,18 +21,18 @@ AlwaysBreakTemplateDeclarations: Yes
 BinPackArguments: true
 BinPackParameters: true
 BraceWrapping:
-  AfterClass:      false
+  AfterClass: false
   AfterControlStatement: false
-  AfterEnum:       false
-  AfterFunction:   false
-  AfterNamespace:  false
+  AfterEnum: false
+  AfterFunction: false
+  AfterNamespace: false
   AfterObjCDeclaration: false
-  AfterStruct:     false
-  AfterUnion:      false
+  AfterStruct: false
+  AfterUnion: false
   AfterExternBlock: false
-  BeforeCatch:     false
-  BeforeElse:      true
-  IndentBraces:    false
+  BeforeCatch: false
+  BeforeElse: true
+  IndentBraces: false
   SplitEmptyFunction: true
   SplitEmptyRecord: true
   SplitEmptyNamespace: true
@@ -45,39 +45,39 @@ BreakConstructorInitializersBeforeComma: true
 BreakConstructorInitializers: BeforeColon
 BreakAfterJavaFieldAnnotations: false
 BreakStringLiterals: true
-ColumnLimit:     160
-CommentPragmas:  '^ IWYU pragma:'
+ColumnLimit: 160
+CommentPragmas: "^ IWYU pragma:"
 CompactNamespaces: false
 ConstructorInitializerAllOnOneLineOrOnePerLine: false
 ConstructorInitializerIndentWidth: 4
 ContinuationIndentWidth: 4
 Cpp11BracedListStyle: true
 DerivePointerAlignment: false
-DisableFormat:   false
+DisableFormat: false
 ExperimentalAutoDetectBinPacking: false
 FixNamespaceComments: true
 ForEachMacros:
   - foreach
   - Q_FOREACH
   - BOOST_FOREACH
-IncludeBlocks:   Preserve
+IncludeBlocks: Preserve
 IncludeCategories:
-  - Regex:           '^"(llvm|llvm-c|clang|clang-c)/'
-    Priority:        2
-  - Regex:           '^(<|"(gtest|gmock|isl|json)/)'
-    Priority:        3
-  - Regex:           '.*'
-    Priority:        1
-IncludeIsMainRegex: '(Test)?$'
+  - Regex: '^"(llvm|llvm-c|clang|clang-c)/'
+    Priority: 2
+  - Regex: '^(<|"(gtest|gmock|isl|json)/)'
+    Priority: 3
+  - Regex: ".*"
+    Priority: 1
+IncludeIsMainRegex: "(Test)?$"
 IndentCaseLabels: false
 IndentPPDirectives: None
-IndentWidth:     4
+IndentWidth: 4
 IndentWrappedFunctionNames: false
 JavaScriptQuotes: Leave
 JavaScriptWrapImports: true
 KeepEmptyLinesAtTheStartOfBlocks: true
-MacroBlockBegin: ''
-MacroBlockEnd:   ''
+MacroBlockBegin: ""
+MacroBlockEnd: ""
 MaxEmptyLinesToKeep: 1
 NamespaceIndentation: All
 ObjCBinPackProtocolList: Auto
@@ -93,8 +93,8 @@ PenaltyBreakTemplateDeclaration: 10
 PenaltyExcessCharacter: 1000000
 PenaltyReturnTypeOnItsOwnLine: 60
 PointerAlignment: Left
-ReflowComments:  true
-SortIncludes:    true
+ReflowComments: true
+SortIncludes: true
 SortUsingDeclarations: true
 SpaceAfterCStyleCast: false
 SpaceAfterTemplateKeyword: false
@@ -106,13 +106,13 @@ SpaceBeforeParens: ControlStatements
 SpaceBeforeRangeBasedForLoopColon: true
 SpaceInEmptyParentheses: false
 SpacesBeforeTrailingComments: 1
-SpacesInAngles:  false
+SpacesInAngles: false
 SpacesInContainerLiterals: true
 SpacesInCStyleCastParentheses: false
 SpacesInParentheses: false
 SpacesInSquareBrackets: false
-Standard:        Cpp11
-TabWidth:        4
-UseTab:          Never
+Standard: Latest
+TabWidth: 4
+UseTab: Never
 ...
 

singleton-smart-pointer-example/CMakeLists.txt → 01-singleton-classic-example/CMakeLists.txt

@@ -1,14 +1,14 @@
 cmake_minimum_required(VERSION 3.21)
-project(singleton-smart-pointer-example VERSION 0.1.0 LANGUAGES CXX)
+project(01-singleton-classic-example VERSION 0.1.0 LANGUAGES CXX)
 
 # Export compile commands for clangd
 set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
 
-add_executable(singleton-smart-pointer-example
+add_executable(01-singleton-classic-example
     src/main.cpp
     src/singleton.cpp
 )
 
-target_include_directories(singleton-smart-pointer-example PRIVATE
+target_include_directories(01-singleton-classic-example PRIVATE
     ${CMAKE_CURRENT_SOURCE_DIR}/inc
 )

singleton-classic-static-example/inc/singleton.h → 01-singleton-classic-example/inc/singleton.h

@@ -10,7 +10,7 @@ class Singleton {
         return instance;
     }
 
-    void func();
+    void info();
 
 private:
     Singleton();

01-singleton-classic-example/src/main.cpp

@@ -0,0 +1,30 @@
+#include "singleton.h"
+#include <iostream>
+#include <thread>
+#include <vector>
+
+/*
+ * Example with static member variable
+ * Static memory allocation
+ * Eager initialization
+ * Singleton is created before main() and destroyed after main() call
+ * Initialization is thread-safe - The static member is initialized before main() in a single-threaded context, so no construction race is possible.
+ * The Static Initialization Order Fiasco - If the singleton instance is accessed during the initialization of another static object.
+ */
+
+int main() {
+    std::cout << "--- main start ---" << std::endl;
+
+    std::vector<std::thread> threads;
+
+    // Launch 10 threads
+    for (int i = 0; i < 10; ++i) {
+        threads.emplace_back([]() { Singleton::getInstance().info(); });
+    }
+
+    for (auto& t : threads) {
+        t.join();
+    }
+
+    std::cout << "--- main end ---" << std::endl;
+}

singleton-classic-static-example/src/singleton.cpp → 01-singleton-classic-example/src/singleton.cpp

@@ -1,14 +1,16 @@
 #include "singleton.h"
 #include <iostream>
+#include <syncstream>
+#include <thread>
 
 Singleton Singleton::instance;
 
 Singleton::Singleton() {
     std::cout << "Singleton created." << std::endl;
 }
 
-void Singleton::func() {
-    std::cout << "Doing something..." << std::endl;
+void Singleton::info() {
+    std::osyncstream(std::cout) << "Current instance address: " << this << " | Current thread ID: " << std::this_thread::get_id() << '\n';
 }
 
 Singleton::~Singleton() {

singleton-classic-static-example/CMakeLists.txt → 02-singleton-meyers-example/CMakeLists.txt

@@ -1,14 +1,14 @@
 cmake_minimum_required(VERSION 3.21)
-project(singleton-classic-static-example VERSION 0.1.0 LANGUAGES CXX)
+project(02-singleton-meyers-example VERSION 0.1.0 LANGUAGES CXX)
 
 # Export compile commands for clangd
 set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
 
-add_executable(singleton-classic-static-example
+add_executable(02-singleton-meyers-example
     src/main.cpp
     src/singleton.cpp
 )
 
-target_include_directories(singleton-classic-static-example PRIVATE
+target_include_directories(02-singleton-meyers-example PRIVATE
     ${CMAKE_CURRENT_SOURCE_DIR}/inc
 )

singleton-meyers-example/inc/singleton.h → 02-singleton-meyers-example/inc/singleton.h

@@ -10,7 +10,7 @@ class Singleton {
         return instance;
     }
 
-    void func();
+    void info();
 
 private:
     Singleton();

singleton-meyers-example/src/main.cpp → 02-singleton-meyers-example/src/main.cpp

@@ -4,7 +4,7 @@
 #include <vector>
 
 /*
- * Meyer’s Singleton - Example with STATIC LOCAL VARIABLE
+ * Meyer’s Singleton - Example with static local variable
  * Static memory allocation
  * Lazy initialization
  * Singleton is created only after first call of getInstance() and destroyed after main() call
@@ -20,7 +20,7 @@ int main() {
 
     // Launch 10 threads
     for (int i = 0; i < 10; ++i) {
-        threads.emplace_back([]() { Singleton::getInstance().func(); });
+        threads.emplace_back([]() { Singleton::getInstance().info(); });
     }
 
     for (auto& t : threads) {

singleton-meyers-example/src/singleton.cpp → 02-singleton-meyers-example/src/singleton.cpp

@@ -1,12 +1,14 @@
 #include "singleton.h"
 #include <iostream>
+#include <syncstream>
+#include <thread>
 
 Singleton::Singleton() {
     std::cout << "Singleton created." << std::endl;
 }
 
-void Singleton::func() {
-    std::cout << "Doing something..." << std::endl;
+void Singleton::info() {
+    std::osyncstream(std::cout) << "Current instance address: " << this << " | Current thread ID: " << std::this_thread::get_id() << '\n';
 }
 
 Singleton::~Singleton() {

03-singleton-classic-dynamic-example/CMakeLists.txt

@@ -0,0 +1,14 @@
+cmake_minimum_required(VERSION 3.21)
+project(03-singleton-classic-dynamic-example VERSION 0.1.0 LANGUAGES CXX)
+
+# Export compile commands for clangd
+set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
+
+add_executable(03-singleton-classic-dynamic-example
+    src/main.cpp
+    src/singleton.cpp
+)
+
+target_include_directories(03-singleton-classic-dynamic-example PRIVATE
+    ${CMAKE_CURRENT_SOURCE_DIR}/inc
+)

singleton-classic-dynamic-example/inc/singleton.h → 03-singleton-classic-dynamic-example/inc/singleton.h

@@ -7,7 +7,7 @@ class Singleton {
 
     static Singleton& getInstance();
     static void delInstance();
-    void func();
+    void info();
 
 private:
     Singleton();

singleton-cherno-example/src/main.cpp → 03-singleton-classic-dynamic-example/src/main.cpp

@@ -2,18 +2,18 @@
 #include <iostream>
 
 /*
- * Example from Cherno with STATIC GLOBAL VARIABLE
+ * Example with static member pointer
  * Dynamic memory allocation
  * Lazy initialization
  * Singleton is created only after first call of getInstance() and destroyed by calling delInstance()
- * Thread-safety not guaranteed
+ * Not Thread-safe
  */
 
 int main() {
     std::cout << "--- main start ---" << std::endl;
 
-    Singleton::getInstance().func();
-
+    Singleton::getInstance().info();
+    Singleton::getInstance().info();
     Singleton::delInstance();
 
     std::cout << "--- main end ---" << std::endl;

singleton-classic-dynamic-example/src/singleton.cpp → 03-singleton-classic-dynamic-example/src/singleton.cpp

@@ -1,5 +1,6 @@
 #include "singleton.h"
 #include <iostream>
+#include <thread>
 
 Singleton* Singleton::instance = nullptr;
 
@@ -21,8 +22,8 @@ Singleton::Singleton() {
     std::cout << "Singleton created." << std::endl;
 }
 
-void Singleton::func() {
-    std::cout << "Doing something..." << std::endl;
+void Singleton::info() {
+    std::cout << "Current instance address: " << this << " | Current thread ID: " << std::this_thread::get_id() << '\n';
 }
 
 Singleton::~Singleton() {

04-singleton-cherno-example/CMakeLists.txt

@@ -0,0 +1,11 @@
+cmake_minimum_required(VERSION 3.21)
+project(04-singleton-cherno-example VERSION 0.1.0 LANGUAGES CXX)
+
+add_executable(04-singleton-cherno-example
+    src/main.cpp
+    src/singleton.cpp
+)
+
+target_include_directories(04-singleton-cherno-example PRIVATE
+    ${CMAKE_CURRENT_SOURCE_DIR}/inc
+)

singleton-cherno-example/inc/singleton.h → 04-singleton-cherno-example/inc/singleton.h

@@ -7,7 +7,7 @@ class Singleton {
 
     static Singleton& getInstance();
     static void delInstance();
-    void func();
+    void info();
 
 private:
     Singleton();

singleton-classic-dynamic-example/src/main.cpp → 04-singleton-cherno-example/src/main.cpp

@@ -2,18 +2,18 @@
 #include <iostream>
 
 /*
- * Example with STATIC MEMBER VARIABLE
+ * Example from Cherno with static global variable in cpp file
  * Dynamic memory allocation
  * Lazy initialization
  * Singleton is created only after first call of getInstance() and destroyed by calling delInstance()
- * Thread-safety not guaranteed
+ * Not Thread-safe
  */
 
 int main() {
     std::cout << "--- main start ---" << std::endl;
 
-    Singleton::getInstance().func();
-    Singleton::getInstance().func();
+    Singleton::getInstance().info();
+    Singleton::getInstance().info();
     Singleton::delInstance();
 
     std::cout << "--- main end ---" << std::endl;

singleton-cherno-example/src/singleton.cpp → 04-singleton-cherno-example/src/singleton.cpp

@@ -1,5 +1,6 @@
 #include "../inc/singleton.h"
 #include <iostream>
+#include <thread>
 
 /* it's private to this file */
 static Singleton* instance = nullptr;
@@ -22,8 +23,8 @@ Singleton::Singleton() {
     std::cout << "Singleton created." << std::endl;
 }
 
-void Singleton::func() {
-    std::cout << "Doing something..." << std::endl;
+void Singleton::info() {
+    std::cout << "Current instance address: " << this << " | Current thread ID: " << std::this_thread::get_id() << '\n';
 }
 
 Singleton::~Singleton() {