Tutorial by Examples: g

// View to hold the CAGradientLayer. let view: UIView = UIView(frame: CGRect(x: 0, y: 0, width: 320, height: 320)) // Initialize gradient layer. let gradientLayer: CAGradientLayer = CAGradientLayer() // Set frame of gradient layer. gradientLayer.frame = view.bounds // Color at...

By default the Python random module use the Mersenne Twister PRNG to generate random numbers, which, although suitable in domains like simulations, fails to meet security requirements in more demanding environments. In order to create a cryptographically secure pseudorandom number, one can use Syst...

docker restart <container> [<container>...] Option --time : Seconds to wait for stop before killing the container (default 10) docker restart <container> --time 10

public class Singleton { private readonly static Singleton instance = new Singleton(); private Singleton() { } public static Singleton Instance => instance; } This implementation is thread-safe because in this case instance object is initialized in the static constructor. The ...

This thread-safe version of a singleton was necessary in the early versions of .NET where static initialization was not guaranteed to be thread-safe. In more modern versions of the framework a statically initialized singleton is usually preferred because it is very easy to make implementation mistak...

git shortlog summarizes git log and groups by author If no parameters are given, a list of all commits made per committer will be shown in chronological order. $ git shortlog Committer 1 (<number_of_commits>): Commit Message 1 Commit Message 2 ... Committer 2 (<number_of_...

When assigning named methods to delegates, they will refer to the same underlying object if: They are the same instance method, on the same instance of a class They are the same static method on a class public class Greeter { public void WriteInstance() { Console.Write...

The following syntax creates a delegate type with name NumberInOutDelegate, representing a method which takes an int and returns an int. public delegate int NumberInOutDelegate(int input); This can be used as follows: public static class Program { static void Main() { Number...

The System namespace contains Func<..., TResult> delegate types with between 0 and 15 generic parameters, returning type TResult. private void UseFunc(Func<string> func) { string output = func(); // Func with a single generic type parameter returns that type Console.WriteLine...

Named methods can be assigned to delegates with matching signatures: public static class Example { public static int AddOne(int input) { return input + 1; } } Func<int,int> addOne = Example.AddOne Example.AddOne takes an int and returns an int, its signature ...

Calling .Equals() on a delegate compares by reference equality: Action action1 = () => Console.WriteLine("Hello delegates"); Action action2 = () => Console.WriteLine("Hello delegates"); Action action1Again = action1; Console.WriteLine(action1.Equals(action1)) // True ...

Lambdas can be used to create anonymous methods to assign to a delegate: Func<int,int> addOne = x => x+1; Note that the explicit declaration of type is required when creating a variable this way: var addOne = x => x+1; // Does not work

PHP will generally correctly guess the data type you intend to use from the context it's used in, however sometimes it is useful to manually force a type. This can be accomplished by prefixing the declaration with the name of the required type in parenthesis: $bool = true; var_dump($bool); // bool...

On either Linux/UNIX or Windows, a script can be passed as an argument to the PHP executable, with that script's options and arguments following: php ~/example.php foo bar c:\php\php.exe c:\example.php foo bar This passes foo and bar as arguments to example.php. On Linux/UNIX, the preferred me...

In Python 2, when a property raise a error, hasattr will ignore this property, returning False. class A(object): @property def get(self): raise IOError class B(object): @property def get(self): return 'get in b' a = A() b = B() print 'a hasattr get:...

The dynamics of the Geometric Brownian Motion (GBM) are described by the following stochastic differential equation (SDE): I can use the exact solution to the SDE to generate paths that follow a GBM. Given daily parameters for a year-long simulation mu = 0.08/250; sigma = 0.25/sqrt(...

int getListOfFriends(size_t size, int friend_indexes[]) { size_t i = 0; for (; i < size; i++) { friend_indexes[i] = i; } } C99C11 /* Type "void" and VLAs ("int friend_indexes[static size]") require C99 at least. In C11 VLAs are optional. */ void getLis...

One of the things that can really boost your productivity while writing the code is effectively navigating the workspace. This also means making it comfortable for the moment. It's possible to achieve this by adjusting which areas of workspaces you see. The buttons on the top of the navigation and ...

When in a loop, the loop variable (val) in the following example is a single variable that changes value as it goes over the loop. Therefore one must do the following to actually pass each val of values to the goroutine: for val := range values { go func(val interface{}) { fmt.Println...

Template may accept both lvalue and rvalue references using forwarding reference: template <typename T> void f(T &&t); In this case, the real type of t will be deduced depending on the context: struct X { }; X x; f(x); // calls f<X&>(x) f(X()); // calls f<X>(...