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Entity systems are how you perform functional operations on sets of entities. Components should typically not have logic associated with them that involves awareness of data or state of other component instances, as that is the job of an entity system. An entity system can not be registered to mor...

Closures are inline anonymous methods that have the ability to use Parent method variables and other anonymous methods which are defined in the parent's scope. In essence, a closure is a block of code which can be executed at a later time, but which maintains the environment in which it was firs...

The IEnumerable<T> interface has a single method, GetEnumerator(), which returns an IEnumerator<T>. While the yield keyword can be used to directly create an IEnumerable<T>, it can also be used in exactly the same way to create an IEnumerator<T>. The only thing that changes ...

A cons cell, also known as a dotted pair (because of its printed representation), is simply a pair of two objects. A cons cell is created by the function cons, and elements in the pair are extracted using the functions car and cdr. (cons "a" 4) For instance, this returns a pair whose ...

Following is most basic expression tree that is created by lambda. Expression<Func<int, bool>> lambda = num => num == 42; To create expression trees 'by hand', one should use Expression class. Expression above would be equivalent to: ParameterExpression parameter = Expression.Pa...

This will create a timer to call the doSomething method on self in 5 seconds. Swift let timer = NSTimer.scheduledTimerWithTimeInterval(5, target: self, selector: Selector(doSomething()), userInfo: nil, ...

Swift timer.fire() Objective-C [timer fire]; Calling the fire method causes an NSTimer to perform the task it would have usually performed on a schedule. In a non-repeating timer, this will automatically invalidate the timer. That is, calling fire before the time interval is up will result ...

Swift timer.invalidate() Objective-C [timer invalidate]; This will stop the timer from firing. Must be called from the thread the timer was created in, see Apple's notes: You must send this message from the thread on which the timer was installed. If you send this message from another thr...

Below won't work on a Windows machine $file = $request->file('file_upload'); $sampleName = 'UserUpload'; $destination = app_path() . '/myStorage/'; $fileName = $sampleName . '-' . date('Y-m-d-H:i:s') . '.' . $file->getClientOriginalExtension(); $file->move($destination, $fileName); ...

Thread synchronization can be accomplished using mutexes, among other synchronization primitives. There are several mutex types provided by the standard library, but the simplest is std::mutex. To lock a mutex, you construct a lock on it. The simplest lock type is std::lock_guard: std::mutex m; vo...

It's simpler and easier to input values as a Python tuple instead of a NumericRange. Book.objects.create(name='Pro Git', ratings_range=(5, 5)) Alternative method with NumericRange: Book.objects.create(name='Pro Git', ratings_range=NumericRange(5, 5))

When using a VCS such as Git or SVN, there are some secret data that must never be versioned (whether the repository is public or private). Among those data, you find the SECRET_KEY setting and the database password. A common practice to hide these settings from version control is to create a file...

The try { ... } catch ( ... ) { ... } control structure is used for handling Exceptions. String age_input = "abc"; try { int age = Integer.parseInt(age_input); if (age >= 18) { System.out.println("You can vote!"); } else { System.out.println(...

Since npm itself is a Node.js module, it can be updated using itself. If OS is Windows must be running command prompt as Admin npm install -g npm@latest If you want to check for updated versions you can do: npm outdated In order to update a specific package: npm update <package name>...

Specific to Windows System and android Phone: Requirements: USB Cable Android Device Android Driver Software Basically after connecting USB cable PC detects the Android Device and it will automatically search for the required Drivers for that Android Device. If that drivers are not found th...

Removing duplicate values in a list can be done by converting the list to a set (that is an unordered collection of distinct objects). If a list data structure is needed, then the set can be converted back to a list using the function list(): names = ["aixk", "duke", "edik&...

In general, an observer is a class with a specific method being called when an action on the observed object occurs. In certain situations, closures can be enough to implement the observer design pattern. Here is a detailed example of such an implementation. Let's first declare a class whose purpos...

We define two sets a and b >>> a = {1, 2, 2, 3, 4} >>> b = {3, 3, 4, 4, 5} NOTE: {1} creates a set of one element, but {} creates an empty dict. The correct way to create an empty set is set(). Intersection a.intersection(b) returns a new set with elements present in bot...

The git commit command does a few things: Create blobs and trees to represent your project directory - stored in .git/objects Creates a new commit object with your author information, commit message, and the root tree from step 1 - also stored in .git/objects Updates the HEAD ref in .git/HEAD t...

Running git checkout -b <refname> will create a new ref that points to the current commit. $ cat .git/head 1f324a $ git checkout -b TestBranch $ cat .git/refs/heads/TestBranch 1f324a