Tutorial by Examples: ha

The easiest method to bypass cache is to change the URL. This is used as a best practice when the URL contains a version or a checksum of the resource, e.g. http://example.com/image.png?version=1 http://example.com/image.png?version=2 These two URLs will be cached separately, so even if …?versi...

To change the URL of the repository you want your remote to point to, you can use the set-url option, like so: git remote set-url <remote_name> <remote_repository_url> Example: git remote set-url heroku https://git.heroku.com/fictional-remote-repository.git

Messages can be sent from JavaScript using the following code window.webkit.messageHandlers.{NAME}.postMessage() Here how to create a script message handler to handle the messages: class NotificationScriptMessageHandler: NSObject, WKScriptMessageHandler { func userContentController(userCon...

IPv4 To match IPv4 address format, you need to check for numbers [0-9]{1,3} three times {3} separated by periods \. and ending with another number. ^(?:[0-9]{1,3}\.){3}[0-9]{1,3}$ This regular expression is too simple - if you want to it to be accurate, you need to check that the numbers are be...

Redux is very functional, so unit testing is very straightforward. Action creator: export function showSidebar () { return { type: 'SHOW_SIDEBAR' } } Action creators unit test: import expect from 'expect' import actions from './actions' import * as type from './constants' desc...

When testing for any of several equality comparisons: if a == 3 or b == 3 or c == 3: it is tempting to abbreviate this to if a or b or c == 3: # Wrong This is wrong; the or operator has lower precedence than ==, so the expression will be evaluated as if (a) or (b) or (c == 3):. The correct w...

Check existing remote git remote -v # origin https://github.com/username/repo.git (fetch) # origin https://github.com/usernam/repo.git (push) Changing repository URL git remote set-url origin https://github.com/username/repo2.git # Change the 'origin' remote's URL Verify new remote URL ...

As a good developer you have created following struct with both exported and unexported fields: type MyStruct struct { uuid string Name string } Example in Playground: https://play.golang.org/p/Zk94Il2ANZ Now you want to Marshal() this struct into valid JSON for storage in somet...

Ruby hashes use the methods hash and eql? to perform the hash operation and assign objects stored in the hash to internal hash bins. The default implementation of hash in Ruby is the murmur hash function over all member fields of the hashed object. To override this behavior it is possible to overrid...

To get current page width and height (for any browser), e.g. when programming responsiveness: function pageWidth() { return window.innerWidth != null? window.innerWidth : document.documentElement && document.documentElement.clientWidth ? document.documentElement.clientWidth : document.bo...

class Message DEFAULT_MESSAGE = "Hello, world" def speak(message = nil) if message puts message else puts DEFAULT_MESSAGE end end end The constant DEFAULT_MESSAGE can be changed with the following code: Message::DEFAULT_MESSAGE = "Hullo, wo...

Reflection is useful when it is properly used for right purpose. By using reflection, you can access private variables and re-initialize final variables. Below is the code snippet, which is not recommended. import java.lang.reflect.*; public class ReflectionDemo{ public static void main(St...

public class InsertIntoConcurrentHashMap { public static void main(String[] args) { ConcurrentHashMap<Integer, SomeObject> concurrentHashMap = new ConcurrentHashMap<>(); SomeObject value = new SomeObject(); Integer key = 1; SomeObject ...

import java.util.ArrayList; import java.util.List; import static java.lang.System.out; public class PolymorphismDemo { public static void main(String[] args) { List<FlyingMachine> machines = new ArrayList<FlyingMachine>(); machines.add(new FlyingMachine())...

Let's say you have this line of code: printf("Hello, world!\n"); Now say you want to change the text to "Program exiting." CommandBufferMnemonicci"printf("¦");change in the ".Program exiting.\n<esc>printf("Program exiting.\n");

You may sometimes want to change the size of a split or vsplit. To change the size of the currently active split, use :resize <new size>. :resize 30 for example would make the split 30 lines tall. To change the size of the currently active vsplit, use :vertical resize <new size>. :vert...

As all threads are running in the same process, all threads have access to the same data. However, concurrent access to shared data should be protected with a lock to avoid synchronization issues. import threading obj = {} obj_lock = threading.Lock() def objify(key, val): print("O...

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() ...

Returns the start index of a the first occurrence of string expression inside another string expression. Parameters list: String to find (up to 8000 chars) String to search (any valid character data type and length, including binary) (Optional) index to start. A number of type int or big int. ...

Returns a char represented by an int ASCII code. SELECT CHAR(116) -- Returns 't' SELECT CHAR(84) -- Returns 'T' This can be used to introduce new line/line feed CHAR(10), carriage returns CHAR(13), etc. See AsciiTable.com for reference. If the argument value is not between 0 and 255, the CHAR...