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Multiton can be used as a container for singletons. This is Multiton implementation is a combination of Singleton and Pool patterns. This is an example of how common Multiton abstract Pool class can be created: abstract class MultitonPoolAbstract { /** * @var array */ protec...

This pattern can be used to contain a registered Pools of Singletons, each distinguished by unique ID: abstract class MultitonRegistryAbstract { /** * @var array */ protected static $instances = []; /** * @param string $id */ final protected function ...

In bash, you have to quote arguments in order to preserve white space: # bash function print_first_argument { echo "$1" } argument="has white space" print_first_argument "$argument" In Zsh, you don't need the quotes, because of different evaluation orde...

To use auto layout we need to enable a boolean flag in storyboard. Its shown in the below image. After this we can use auto layout in our storyboard. There is another option if we want to use size classes or not. Size class is also a helpful option in auto layout which helps us to design for differe...

A pattern rule is indicated by a single % character in the target. The % matches a non-empty string called the stem. The stem is then substituted for every % that appears in the prerequisite list. For example, this rule: %.o: %.c $(CC) $(CFLAGS) -c $< -o $@ Will match any target ending ...

If a target matches multiple pattern rules, make will use the one whose prerequisites exist or can be built. For example: %.o: %.c $(CC) $(CFLAGS) -c $< -o $@ %.o: %.s $(AS) $(ASFLAGS) $< -o $@ Will compile foo.c to foo.o or assemble foo.s to foo.o, depending on which one of foo...

If the target pattern doesn't contain slashes, make will remove the directory part from the target it's trying to build before matching. The directory will then be put in front of the stem. When the stem is used to build the target name and prerequisites, the directory part is stripped from it, the ...

Pattern rules can have multiple targets but, unlike normal rules, the recipe is responsible for making all the targets. For example: debug/%.o release/%.o: %.c $(CC) $(CFLAGS_DEBUG) -c $< -o debug/$*.o $(CC) $(CFLAGS_RELEASE) -c $< -o release/$*.o Is a valid rule, which will buil...

Introduced in iOS 9, all endpoints must adhere to the HTTPS specification. Any endpoints not using SSL will fail with a warning in the console log. To your application it will appear that the internet connection failed. To configure exceptions: Place the following in your Info.plist file: Allow...

To enable the ripple animation in a CardView, add the following attributes: <android.support.v7.widget.CardView ... android:clickable="true" android:foreground="?android:attr/selectableItemBackground"> ... </android.support.v7.widget.CardView>

If you want to add a UIImageView to the center of the screen with width and height of 100 pixel, you need to set center x constraint and center y constraint to the superview from the UIImageView and width, height constraint to the UIIMageView. Here is the code. There is way to do this in storyboard ...

Detailed instructions on getting google-cloud-platform set up or installed.

A NullReferenceException is thrown when you try to access a non-static member (property, method, field or event) of a reference object but it is null. Car myFirstCar = new Car(); Car mySecondCar = null; Color myFirstColor = myFirstCar.Color; // No problem as myFirstCar exists / is not null Color...

PHPUnit provides the following functions to watch for thrown exceptions, which were released with 5.2.0: expectException($exception) expectExceptionMessage($message) expectExceptionCode($code) expectExceptionMessageRegExp($messageRegExp) These are used to watch for an exception to be thrown...

If you need to listen for changes to the page selected you can implement the ViewPager.OnPageChangeListener listener on the ViewPager: viewPager.addOnPageChangeListener(new OnPageChangeListener() { // This method will be invoked when a new page becomes selected. Animation is not necessar...

public class CreateAnArray{ public static void main(String[] args){ // Creates a new array of Strings with a length of 3 // This length cannot be changed later String[] myStringArray = new String[3]; myStringArray[0] = "Hello"; // Java array ind...

public class CreateArrayWithValues { public static void main(String[] args){ // Initializes an array of Strings with values String[] myArray = {"this", "array", "has", "six", "initial", "values"}; System.out....

Problem statement: Find the minimum (over x, y) of the function f(x,y), subject to g(x,y)=0, where f(x,y) = 2 * x**2 + 3 * y**2 and g(x,y) = x**2 + y**2 - 4. Solution: We will solve this problem by performing the following steps: Specify the Lagrangian function for the problem Determine the K...

Xamarin is becoming more and more popular - it is hard to decide when to use Xamarin.Forms and when Xamarin.Platform (so Xamarin.iOS and Xamarin.Android). First of all you should know for what kind of applications you can use Xamarin.Forms: Prototypes - to visualize how your application will l...

Detailed instructions on getting scenekit set up or installed.