Merge remote-tracking branch 'upstream/master'

Conflicts:
	perl6.html.markdown

1 files changed, 138 insertions, 11 deletions

diff --git a/c++.html.markdown b/c++.html.markdown
index 1a84efa4..ff2a98fd 100644
--- a/c++.html.markdown
+++ b/c++.html.markdown
@@ -32,8 +32,7 @@ one of the most widely-used programming languages.
 // variable declarations, primitive types, and functions.
 
 // Just like in C, your program's entry point is a function called
-// main with an integer return type,
-// though void main() is also accepted by most compilers (gcc, clang, etc.)
+// main with an integer return type.
 // This value serves as the program's exit status.
 // See http://en.wikipedia.org/wiki/Exit_status for more information.
 int main(int argc, char** argv)
@@ -289,7 +288,7 @@ public:
 
     // Functions can also be defined inside the class body.
     // Functions defined as such are automatically inlined.
-    void bark() const { std::cout << name << " barks!\n" }
+    void bark() const { std::cout << name << " barks!\n"; }
 
     // Along with constructors, C++ provides destructors.
     // These are called when an object is deleted or falls out of scope.
@@ -301,7 +300,7 @@ public:
 }; // A semicolon must follow the class definition.
 
 // Class member functions are usually implemented in .cpp files.
-void Dog::Dog()
+Dog::Dog()
 {
     std::cout << "A dog has been constructed\n";
 }
@@ -324,7 +323,7 @@ void Dog::print() const
     std::cout << "Dog is " << name << " and weighs " << weight << "kg\n";
 }
 
-void Dog::~Dog()
+Dog::~Dog()
 {
     cout << "Goodbye " << name << "\n";
 }
@@ -333,7 +332,7 @@ int main() {
     Dog myDog; // prints "A dog has been constructed"
     myDog.setName("Barkley");
     myDog.setWeight(10);
-    myDog.printDog(); // prints "Dog is Barkley and weighs 10 kg"
+    myDog.print(); // prints "Dog is Barkley and weighs 10 kg"
     return 0;
 } // prints "Goodbye Barkley"
 
@@ -342,7 +341,7 @@ int main() {
 // This class inherits everything public and protected from the Dog class
 class OwnedDog : public Dog {
 
-    void setOwner(const std::string& dogsOwner)
+    void setOwner(const std::string& dogsOwner);
 
     // Override the behavior of the print function for all OwnedDogs. See
     // http://en.wikipedia.org/wiki/Polymorphism_(computer_science)#Subtyping
@@ -426,7 +425,7 @@ int main () {
     Point up (0,1);
     Point right (1,0);
     // This calls the Point + operator
-    // Point up calls the + (function) with right as its paramater
+    // Point up calls the + (function) with right as its parameter
     Point result = up + right;
     // Prints "Result is upright (1,1)"
     cout << "Result is upright (" << result.x << ',' << result.y << ")\n";
@@ -434,6 +433,85 @@ int main () {
 }
 
 /////////////////////
+// Templates
+/////////////////////
+
+// Templates in C++ are mostly used for generic programming, though they are
+// much more powerful than generics constructs in other languages. It also
+// supports explicit and partial specialization, functional-style type classes,
+// and also it's Turing-complete.
+
+// We start with the kind of generic programming you might be familiar with. To
+// define a class or function that takes a type parameter:
+template<class T>
+class Box {
+public:
+    // In this class, T can be used as any other type.
+    void insert(const T&) { ... }
+};
+
+// During compilation, the compiler actually generates copies of each template
+// with parameters substituted, and so the full definition of the class must be
+// present at each invocation. This is why you will see template classes defined
+// entirely in header files.
+
+// To instantiate a template class on the stack:
+Box<int> intBox;
+
+// and you can use it as you would expect:
+intBox.insert(123);
+
+// You can, of course, nest templates:
+Box<Box<int> > boxOfBox;
+boxOfBox.insert(intBox);
+
+// Up until C++11, you must place a space between the two '>'s, otherwise '>>'
+// will be parsed as the right shift operator.
+
+// You will sometimes see
+//   template<typename T>
+// instead. The 'class' keyword and 'typename' keyword are _mostly_
+// interchangeable in this case. For full explanation, see
+//   http://en.wikipedia.org/wiki/Typename
+// (yes, that keyword has its own Wikipedia page).
+
+// Similarly, a template function:
+template<class T>
+void barkThreeTimes(const T& input)
+{
+    input.bark();
+    input.bark();
+    input.bark();
+}
+
+// Notice that nothing is specified about the type parameters here. The compiler
+// will generate and then type-check every invocation of the template, so the
+// above function works with any type 'T' that has a const 'bark' method!
+
+Dog fluffy;
+fluffy.setName("Fluffy")
+barkThreeTimes(fluffy); // Prints "Fluffy barks" three times.
+
+// Template parameters don't have to be classes:
+template<int Y>
+void printMessage() {
+  cout << "Learn C++ in " << Y << " minutes!" << endl;
+}
+
+// And you can explicitly specialize templates for more efficient code. Of
+// course, most real-world uses of specialization are not as trivial as this.
+// Note that you still need to declare the function (or class) as a template
+// even if you explicitly specified all parameters.
+template<>
+void printMessage<10>() {
+  cout << "Learn C++ faster in only 10 minutes!" << endl;
+}
+
+printMessage<20>();  // Prints "Learn C++ in 20 minutes!"
+printMessage<10>();  // Prints "Learn C++ faster in only 10 minutes!"
+
+
+/////////////////////
 // Exception Handling
 /////////////////////
 
@@ -441,12 +519,13 @@ int main () {
 // (see http://en.cppreference.com/w/cpp/error/exception)
 // but any type can be thrown an as exception
 #include <exception>
+#include <stdexcept>
 
 // All exceptions thrown inside the _try_ block can be caught by subsequent
 // _catch_ handlers.
 try {
     // Do not allocate exceptions on the heap using _new_.
-    throw std::exception("A problem occurred");
+    throw std::runtime_error("A problem occurred");
 }
 // Catch exceptions by const reference if they are objects
 catch (const std::exception& ex)
@@ -537,7 +616,7 @@ void doSomethingWithAFile(const char* filename)
 {
     FILE* fh = fopen(filename, "r"); // Open the file in read mode
     if (fh == nullptr)
-        throw std::exception("Could not open the file.");
+        throw std::runtime_error("Could not open the file.");
 
     try {
         doSomethingWithTheFile(fh);
@@ -586,8 +665,56 @@ void doSomethingWithAFile(const std::string& filename)
 //   vector (i.e. self-resizing array), hash maps, and so on
 //   all automatically destroy their contents when they fall out of scope.
 // - Mutexes using lock_guard and unique_lock
+
+
+/////////////////////
+// Fun stuff
+/////////////////////
+
+// Aspects of C++ that may be surprising to newcomers (and even some veterans).
+// This section is, unfortunately, wildly incomplete; C++ is one of the easiest
+// languages with which to shoot yourself in the foot.
+
+// You can override private methods!
+class Foo {
+  virtual void bar();
+};
+class FooSub : public Foo {
+  virtual void bar();  // overrides Foo::bar!
+};
+
+
+// 0 == false == NULL (most of the time)!
+bool* pt = new bool;
+*pt = 0;  // Sets the value points by 'pt' to false.
+pt = 0;  // Sets 'pt' to the null pointer. Both lines compile without warnings.
+
+// nullptr is supposed to fix some of that issue:
+int* pt2 = new int;
+*pt2 = nullptr;  // Doesn't compile
+pt2 = nullptr;  // Sets pt2 to null.
+
+// But somehow 'bool' type is an exception (this is to make `if (ptr)` compile).
+*pt = nullptr;  // This still compiles, even though '*pt' is a bool!
+
+
+// '=' != '=' != '='!
+// Calls Foo::Foo(const Foo&) or some variant copy constructor.
+Foo f2;
+Foo f1 = f2;
+
+// Calls Foo::Foo(const Foo&) or variant, but only copies the 'Foo' part of
+// 'fooSub'. Any extra members of 'fooSub' are discarded. This sometimes
+// horrifying behavior is called "object slicing."
+FooSub fooSub;
+Foo f1 = fooSub;
+
+// Calls Foo::operator=(Foo&) or variant.
+Foo f1;
+f1 = f2;
+
 ```
-Futher Reading:
+Further Reading:
 
 An up-to-date language reference can be found at
 <http://cppreference.com/w/cpp>