Tutorial by Examples: ce

In Swift, memory management is done for you automatically using Automatic Reference Counting. (See Memory Management) Allocation is the process of reserving a spot in memory for an object, and in Swift understanding the performance of such requires some understanding of the heap and the stack. The h...

With ASP.NET Core the Microsoft team also introduced the Options pattern, which allows to have strong typed options and once configured the ability to inject the options into your services. First we start with a strong typed class, which will hold our configuration. public class MySettings { ...

--dataset schemas must be identical SELECT 'Data1' as 'Column' UNION ALL SELECT 'Data2' as 'Column' UNION ALL SELECT 'Data3' as 'Column' UNION ALL SELECT 'Data4' as 'Column' UNION ALL SELECT 'Data5' as 'Column' EXCEPT SELECT 'Data3' as 'Column' --Returns Data1, Data2, Data4, and Data5

Counting references on strings is thread-safe. Locks and exception handlers are used to safeguard the process. Consider the following code, with comments indicating where the compiler inserts code at compile time to manage reference counts: procedure PassWithNoModifier(S: string); // prologue: Inc...

Java provides the instanceof operator to test if an object is of a certain type, or a subclass of that type. The program can then choose to cast or not cast that object accordingly. Object obj = Calendar.getInstance(); long time = 0; if(obj instanceof Calendar) { time = ((Calendar)obj).ge...

It can be useful to load a resource (image, text file, properties, KeyStore, ...) that is packaged inside a JAR. For this purpose, we can use the Class and ClassLoaders. Suppose we have the following project structure : program.jar | \-com \-project | |-file.txt \-Test.class ...

Instance variables have an object wide scope, they can be declared anywhere in the object, however an instance variable declared on class level, will only be visible in the class object. A variable will be considered an instance variable when prefixed with @. Instance variables are used to set and g...

public void SaveNewEmployee(Employee newEmployee) { // best practice - wrap all database connections in a using block so they are always closed & disposed even in the event of an Exception // best practice - retrieve the connection string by name from the app.config or web.config (dep...

C++17 namespace a { namespace b { template<class T> struct qualifies : std::false_type {}; } } namespace other { struct bob {}; } namespace a::b { template<> struct qualifies<::other::bob> : std::true_type {}; } You can enter both the a and b n...

var baseType = typeof(List<>); var genericType = baseType.MakeGenericType(typeof(String)); var instance = Activator.CreateInstance(genericType); var method = genericType.GetMethod("GetHashCode"); var result = method.Invoke(instance, new object[] { });

import java.io.FileReader; import java.io.IOException; import javax.script.ScriptEngine; import javax.script.ScriptEngineManager; import javax.script.ScriptException; public class InterfaceImplementationExample { public static interface Pet { public void eat(); } p...

An important principle for unit testing is to separate data access from business logic. One efficient technique for this is to define interfaces for data access. Your main class always use a reference to that interface instead of direct reading or writing data. in production code the main class wil...

Suppose we want to select a word with a surrounding white space, use the text object aw for around a word using visual mode: Got to normal mode by pressing ESC Type vaw at the beginning of a word This will select the word with white space

This substitute command can use Regular Expressions and will match any instance of foo followed by any( one ) character since the period . in Regular Expressions matches any character, hence the following command will match all instances of foo followed by any character in the current line. :s/foo....

Instead of web pages, we can also load the document files into iOS WebView like .pdf, .txt, .doc etc.. loadData method is used to load NSData into webview. Swift //Assuming there is a text file in the project named "home.txt". let localFilePath = NSBundle.mainBundle().pathForResource(&...

Use multiprocessing.Process to run a function in another process. The interface is similar to threading.Thread: import multiprocessing import os def process(): print("Pid is %s" % (os.getpid(),)) processes = [multiprocessing.Process(target=process) for _ in range(4)] for p in...

Code running in different processes do not, by default, share the same data. However, the multiprocessing module contains primitives to help share values across multiple processes. import multiprocessing plain_num = 0 shared_num = multiprocessing.Value('d', 0) lock = multiprocessing.Lock() ...

Place Picker is a really simple UI widget provided by Places API. It provides a built-in map, current location, nearby places, search abilities and autocomplete. This is a sample usage of Place Picker UI widget. private static int PLACE_PICKER_REQUEST = 1; private TextView txtPlaceName; @Ove...

You can get the current location and local places of user by using the Google Places API. Ar first, you should call the PlaceDetectionApi.getCurrentPlace() method in order to retrieve local business or other places. This method returns a PlaceLikelihoodBuffer object which contains a list of PlaceLi...

An interface contains the signatures of methods, properties and events. The derived classes defines the members as the interface contains only the declaration of the members. An interface is declared using the interface keyword. interface IProduct { decimal Price { get; } } class Product...