diff --git a/notebooks/08_Functors+Lambdas.ipynb b/notebooks/08_Functors+Lambdas.ipynb
index 8df7e34bb315562c3ab8d265894fc37c3f956850..90682ed36058bfe3ae5ede117cf9de88b6b2dbc3 100644
--- a/notebooks/08_Functors+Lambdas.ipynb
+++ b/notebooks/08_Functors+Lambdas.ipynb
@@ -76,7 +76,7 @@
"#### Functors\n",
"In C++ we can as one alternative use a **function object**, a.k.a. **functor**. This is an object of a class that overloads the function call operator ```operator()```.\n",
"\n",
- "**Example #1:**"
+ "##### **Example 1:**"
]
},
{
@@ -135,7 +135,7 @@
"***\n",
"Now that was a simple functor and did only demonstrate **how** it works and not **why** that approach can be advantageous.\n",
"\n",
- "**Example 2:** \n",
+ "##### **Example 2:** \n",
"In our second example we will use a stateful functor that allows to perform different binary operations. The type of operation will be passed via its constructor."
]
},
@@ -216,7 +216,7 @@
"id": "6adaab27",
"metadata": {},
"source": [
- "**Example 3:** \n",
+ "##### **Example 3:** \n",
"So how would our set example for myPair look like with a functor?"
]
},
@@ -308,6 +308,208 @@
"!./a.out"
]
},
+ {
+ "cell_type": "markdown",
+ "id": "c51deb94-f9c2-4a88-914b-ddf70f29601e",
+ "metadata": {},
+ "source": [
+ "#### std::function\n",
+ "\n",
+ "Quoting from cppreference:\n",
+ "> Class template std::function is a general-purpose polymorphic function wrapper. Instances of std::function can store, copy, and invoke any CopyConstructible Callable target -- functions, lambda expressions, bind expressions, or other function objects, as well as pointers to member functions and pointers to data members.\n",
+ ">\n",
+ "> The stored callable object is called the target of std::function. If a std::function contains no target, it is called empty. Invoking the target of an empty std::function results in std::bad_function_call exception being thrown. \n",
+ "\n",
+ "The functionality of ```std::function``` is quite useful especially in combination with lambda functions (see below)."
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "id": "6c584ecb-10c3-4ff2-ab53-2a66c0963009",
+ "metadata": {},
+ "source": [
+ "##### **Example 4:**\n",
+ "Assign a simple free-function"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": 11,
+ "id": "21120bbb-03a7-4048-97f4-0426c40c5bac",
+ "metadata": {},
+ "outputs": [],
+ "source": [
+ "#include <iostream>\n",
+ "void sayIt() { std::cout << \"He said captain, I said wot\" << std::endl; }"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": 12,
+ "id": "bab0ab95-e5fd-4368-b3c2-77bcb869cfe0",
+ "metadata": {},
+ "outputs": [],
+ "source": [
+ "// generate an object of type std::function;\n",
+ "\n",
+ "// need this header file\n",
+ "#include <functional>\n",
+ "\n",
+ "// need to supply the prototype of the function/invocation that we want to target\n",
+ "std::function< void( ) > sensible;"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": 13,
+ "id": "b4e3f68a-6c70-49e7-a04c-924804c4cb35",
+ "metadata": {},
+ "outputs": [
+ {
+ "name": "stdout",
+ "output_type": "stream",
+ "text": [
+ "empty -> nothing to do!\n"
+ ]
+ }
+ ],
+ "source": [
+ "// std::function overloads 'operator bool' so we can check if anything is targetted, yet\n",
+ "if( !sensible ) {\n",
+ " std::cout << \"empty -> nothing to do!\" << std::endl;\n",
+ "}"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": 14,
+ "id": "c5b3e4d0-64b4-47c6-848f-f787bf9c0b17",
+ "metadata": {},
+ "outputs": [
+ {
+ "name": "stdout",
+ "output_type": "stream",
+ "text": [
+ "He said captain, I said wot\n"
+ ]
+ }
+ ],
+ "source": [
+ "// now assign a target to our std::object\n",
+ "sensible = sayIt;\n",
+ "\n",
+ "// and perform the invocation\n",
+ "sensible();"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "id": "1ad030ff-9527-4436-be80-72baf9ac7b29",
+ "metadata": {},
+ "source": [
+ "##### **Example 5:**\n",
+ "Now lets use a functor with a slightly more complicated interface"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": 15,
+ "id": "ff8d558b-da83-46d9-9842-8e0d9d5ba56d",
+ "metadata": {},
+ "outputs": [],
+ "source": [
+ "// that's our functor\n",
+ "struct Mult {\n",
+ " int operator() ( int a, int b ) { return a*b; } \n",
+ "}"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": 16,
+ "id": "b5790b96-bf62-4d6e-ad9c-e56839882728",
+ "metadata": {},
+ "outputs": [
+ {
+ "data": {
+ "text/plain": [
+ "6"
+ ]
+ },
+ "execution_count": 16,
+ "metadata": {},
+ "output_type": "execute_result"
+ }
+ ],
+ "source": [
+ "// if we want, we can alias our std::function type\n",
+ "using binaryOp = std::function< int(int,int) >;\n",
+ "\n",
+ "// now instantiate an object that targets the functor\n",
+ "binaryOp multiply = Mult();\n",
+ "\n",
+ "// note that we needed the () to differentiate between the invocation and the functor itself!\n",
+ "\n",
+ "multiply(2,3)"
+ ]
+ },
+ {
+ "cell_type": "markdown",
+ "id": "589b7083-7a36-4ff8-bdd0-c46f9994228c",
+ "metadata": {},
+ "source": [
+ "##### **Example 6:**\n",
+ "A member function of a class can also serve as target"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": 18,
+ "id": "646b302f-cdf5-40ed-98f8-01d98a9b277a",
+ "metadata": {},
+ "outputs": [],
+ "source": [
+ "struct ItemsInStore{\n",
+ " int num;\n",
+ " ItemsInStore() = delete;\n",
+ " ItemsInStore( int num ) : num(num) {};\n",
+ " void decrementAndShowRest() {\n",
+ " std::cout << \"Only \" << --num << \" items left!\" << std::endl;\n",
+ " }\n",
+ "};"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": 19,
+ "id": "b56b370a-654f-4665-a86d-1b4a1497a813",
+ "metadata": {},
+ "outputs": [],
+ "source": [
+ "std::function< void( ItemsInStore& ) > takeOne = &ItemsInStore::decrementAndShowRest;"
+ ]
+ },
+ {
+ "cell_type": "code",
+ "execution_count": 20,
+ "id": "b267e62f",
+ "metadata": {},
+ "outputs": [
+ {
+ "name": "stdout",
+ "output_type": "stream",
+ "text": [
+ "Only 4 items left!\n",
+ "Only 3 items left!\n"
+ ]
+ }
+ ],
+ "source": [
+ "ItemsInStore candyBox( 5 );\n",
+ "takeOne( candyBox );\n",
+ "takeOne( candyBox );"
+ ]
+ },
{
"cell_type": "markdown",
"id": "9d2c9715",