Tutorial by Examples: s

Move semantics are a way of moving one object to another in C++. For this, we empty the old object and place everything it had in the new object. For this, we must understand what an rvalue reference is. An rvalue reference (T&& where T is the object type) is not much different than a norma...

Say we have this code snippet. class A { public: int a; int b; A(const A &other) { this->a = other.a; this->b = other.b; } }; To create a copy constructor, that is, to make a function that copies an object and creates a new one, we norma...

Similarly to how we can assign a value to an object with an lvalue reference, copying it, we can also move the values from an object to another without constructing a new one. We call this move assignment. We move the values from one object to another existing object. For this, we will have to over...

The normal orElse method takes an Object, so you might wonder why there is an option to provide a Supplier here (the orElseGet method). Consider: String value = "something"; return Optional.ofNullable(value) .orElse(getValueThatIsHardToCalculate()); // returns "some...

A static member function is just like an ordinary C/C++ function, except with scope: It is inside a class, so it needs its name decorated with the class name; It has accessibility, with public, protected or private. So, if you have access to the static member function and decorate it correctl...

To access a member function of a class, you need to have a "handle" to the particular instance, as either the instance itself, or a pointer or reference to it. Given a class instance, you can point to various of its members with a pointer-to-member, IF you get the syntax correct! Of course...

To access a member of a class, you need to have a "handle" to the particular instance, as either the instance itself, or a pointer or reference to it. Given a class instance, you can point to various of its members with a pointer-to-member, IF you get the syntax correct! Of course, the poi...

A static member variable is just like an ordinary C/C++ variable, except with scope: It is inside a class, so it needs its name decorated with the class name; It has accessibility, with public, protected or private. So, if you have access to the static member variable and decorate it correctl...

sp_who2 This procedure can be used to find information on current SQL server sessions. Since it is a procedure, it's often helpful to store the results into a temporary table or table variable so one can order, filter, and transform the results as needed. The below can be used for a queryable v...

To create a mixin use the @mixin directive. @mixin default-box ($color, $borderColor) { color: $color; border: 1px solid $borderColor; clear: both; display: block; margin: 5px 0; padding: 5px 10px; } You can specify a list of arguments inside a parenthesis followin...

string nullString = null; string emptyString = ""; string whitespaceString = " "; string tabString = "\t"; string newlineString = "\n"; string nonEmptyString = "abc123"; bool result; result = String.IsNullOrEmpty(nullString); ...

Declaring a generic interface interface IResult<T> { wasSuccessfull: boolean; error: T; } var result: IResult<string> = .... var error: string = result.error; Generic interface with multiple type parameters interface IRunnable<T, U> { run(input: T): U; } ...

class Result<T> { constructor(public wasSuccessful: boolean, public error: T) { } public clone(): Result<T> { ... } } let r1 = new Result(false, 'error: 42'); // Compiler infers T to string let r2 = new Result(false, 42); // Compiler infers T...

Simple constraint: interface IRunnable { run(): void; } interface IRunner<T extends IRunnable> { runSafe(runnable: T): void; } More complex constraint: interface IRunnble<U> { run(): U; } interface IRunner<T extends IRunnable<U>, U> { runSafe...

In interfaces: interface IRunner { runSafe<T extends IRunnable>(runnable: T): void; } In classes: class Runner implements IRunner { public runSafe<T extends IRunnable>(runnable: T): void { try { runnable.run(); } catch(e) { } ...

Create generic class instance: var stringRunnable = new Runnable<string>(); Run generic function: function runSafe<T extends Runnable<U>, U>(runnable: T); // Specify the generic types: runSafe<Runnable<string>, string>(stringRunnable); // Let typescript figu...

Using the mmap module allows the user to randomly access locations in a file by mapping the file into memory. This is an alternative to using normal file operations. import mmap with open('filename.ext', 'r') as fd: # 0: map the whole file mm = mmap.mmap(fd.fileno(), 0) # print ...

If you are familiar with jQuery and Sizzle syntax, d3 selections should not be much different. d3 mimics the W3C Selectors API to make interacting with elements easier. For a basic example, to select all <p> and add a change to each of them: d3.selectAll('p') .attr('class','textClass') ...

Signals and slots are used for communication between objects. The signals and slots mechanism is a central feature of Qt and probably the part that differs most from the features provided by other frameworks. The minimal example requires a class with one signal, one slot and one connection: counte...

The lubridate package provides convenient functions to format date and datetime objects from character strings. The functions are permutations of LetterElement to parseBase R equivalentyyear%y, %Ym (with y and d)month%m, %b, %h, %Bdday%d, %ehhour%H, %I%pm (with h and s)minute%Msseconds%S e.g. ymd(...