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  Fix issue "cannot load such file -- bcrypt_ext (LoadError)"

bcrypt() is a sophisticated and secure hash algorithm designed by The OpenBSD project for hashing passwords. The bcrypt Ruby gem provides a simple wrapper for safely handling passwords. However, sometimes the rails application would fail to start after installing the bcrypt gem on Windows. The error would look similar to below. The issue is that it fails to load the bcrypt_ext which is the native built extension, the reason may be the library is wrongly built. To fix this issue, below steps can...

   RUBY,SOLUTION,RUBY ON RAILS,BCRYPT,LOAD ERROR     2017-03-05 00:21:10

  An alternative way to parse URL in JavaScript

Normally when we need to process URL in JavaScript, we may use the location object. Then we can use location.hostname,location.href,location.port etc to get the information we need. In this post, we will parse an URL with an alternative way. We can use an URL to create a DOM object by calling document.createElement("a"). The complete code is: function parseURL(url) { var a = document.createElement('a'); a.href = url; return { source: url, protocol: a.protocol.replace(':',''), host: a.ho...

   URL,location,parse     2014-03-03 07:05:11

  Maintain multiple versions of Go in one single environment

In a development environment, there might be multiple projects going on at the same time and they may require different development environments with different versions of build tool. In many programming languages, it is possible to have multiple versions of different build tool or development tool on a single environment. For example, there can be multiple JDKs, multiple versions of Ruby using RVM. For GoLang, there is a similar tool called GVM which can also be used to maintain multiple versio...

   GOLANG,GVM,GVM PKGSET,RVM     2019-11-10 00:43:47

  Mutli-inheritance bug between python 2.7 and 3.7

When we have run a py3.7 code under py2.x or a py2.x code under 3.x ,if a class do mutli-inheritance from 2 parent and the 2 parents also got inheritance from same parent, the different way to handle inheritance chain between python 2 and 3 will cause some running time bug: Assume we got this sample program inheritTest.py : # Purpose: Test mutli-inheritance different between python2 and 3 # Author: Yuancheng Liu # Created: 2019/05/16 class A: def getVal(self): print("cal...

   PYTHON,PYTHON 3,INHERITANCE     2019-05-16 08:33:52

  Guide to Implement an SSH Client Using Golang

SSH, short for Secure Shell, is a network protocol used for securely remote logging into other computers on a network. I believe most backend developers are familiar with SSH. Common shell tools used for logging into servers, such as Xshell, SecureCRT, and iTerm2, are all based on the SSH protocol. In Golang, the crypto/ssh package provides functionality for implementing an SSH client. In this article, we will explain in detail how to implement an SSH client using Golang. Creating SSH Client Con...

   SSH CLIENT,GUIDE,SSH,GOLANG     2023-11-11 09:19:29

  4 asynchronous programming methods in JavaScript

You may know the execution environment of JavaScript is single threaded. The so called single thread means only one task can be running at any time, if there are many tasks, they need to be in a queue and wait for the previous task to be completed. The advantage of this mode is it's easy to implement and the execution environment is relative simple; the disadvantage is that if one task takes long time, the tasks following it must wait in the queue and this will delay other tasks consequently. Th...

   JAVASCRIPT,ASYNCHRONOUS PROGRAMMING, EVENT MODEL,PROMISE     2012-12-25 00:55:47

  How to reset root password in MySQL 8

The user password in MySQL is stored in the user table, the password reset is actually to change the value of record in this table. To change the password in case the password is forgotten, the idea is to bypass the authentication of MySQL and get into the system and update the record password value with SQL command. In MySQL 5, one can start MySQL service with --skip-grant-tables option, this option will tell the service to skip loading the grant tables when starting, hence the root user can lo...

   MYSQL,PASSWORD,MYSQL 8     2018-12-24 21:27:13

  Parallel Javascript

Lately the ideas for a parallel, shared memory JavaScript have begun to take shape. I’ve been discussing with various JavaScript luminaries and it seems like a design is starting to emerge. This post serves as a documentation of the basic ideas; I’m sure the details will change as we go along. User Model The model is that a JavaScript worker (the “parent”) may spawn a number of child tasks (the “children”). The parent is suspended while the children exe...

   Parallel JavaScript,API,Spawn,Parent,Task     2012-01-11 12:02:00

  C++, Ruby and CoffeeScript complexity comparison

There are many programming languages around the world, they all designed to help programmer solve some problems, finish some tasks. These languages are often divided into different types, there are structural, object-oriented, functional, scripting languages etc. Some are easy to pick up such as Java, while some are thought to be difficult to learn such as C++. So how do we understand complexities of different programming languages?Many people agree that C++ is very complex languages, it has poi...

   Complexity, languages, C++,Ruby,CoffeeScript     2012-06-12 04:46:01

  Understand JavaScript prototype

For an front end programming language like JavaScript, if we want to understand its OOP feature, we need to understand its objects, prototype chain, execution context, closure and this keyword in deep. If you have a good understanding on these concepts, you should be confident that you can handle this language well. The inheritance in JavaScript is not class inheritance like Java, but it adopts another mechanism-- prototype inheritance. The key to prototype inheritance is the prototype chain mec...

   JavaScript, prototype, __proto__     2013-02-02 02:34:09

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