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  Be careful about printing error as string in GoLang

In GoLang, we can format and produce string using fmt.Printf(), just like C, GoLang also supports format verbs like %s, %d which can be placeholder for different types of values. But please pay attention when printing error as string so that you will not fall into some trap. Let's first take an example code snippet and see what trap we are talking about. package main import "fmt" type A string func (a A) Error() string { return fmt.Sprintf("%s is an error", a) } func main() { a := A("hello...

   STACKOVERFLOW,GOLANG,FMT     2019-01-23 09:17:15

  Some cases where MySQL cannot be started

After installing MySQL, when we try to start MySQL, sometimes we may not be able to start it. The reasons can be different. We share some general cases where MySQL cannot be started. Case 1: Directory or file permission issue If the permission is set wrongly in MySQL's $datadir and its sub directories or files, MySQL will not be able to read and write files normally. Error message: mysqld_safe Starting mysqld daemon with databases from /usr/local/mysql/data /usr/local/mysql/bin/mysqld_safe: lin...

   MySQL,Error,Log     2013-08-15 03:32:36

  Be careful about nil check on interface in GoLang

nil check is frequently seen in GoLang code especially for error check since GoLang's special error handling convention. In most cases, nil check is straight forward, but in interface case, it's a bit different and special care needs to be taken. Take a look at below code snippet and guess what the output will be. package main import ( "bytes" "fmt" "io" ) func check(w io.Writer) { if w != nil { fmt.Println("w is not nil") } fmt.Printf("w is %+v\n", w) } func main() { var b *bytes.B...

   INTERFACE,GOLANG,NIL CHECK,NIL TYPE,NIL VALUE     2019-04-06 07:47:07

  Handle ”cannot modify header information – headers already sent by”

Man PHP developers should encounter ”Warning: Cannot modify header information – headers already sent by ….” error before when executing a PHP script. Here are some solutions to this error. 1. Blank line Check whether there is any blank line after , especially in the files which are used in include() and require(0, some problems are caused by blank lines. 2. Add exit() after head() header (“Location: xxx”); exit(); 3. Use output cache <?php ob_start(); ...

   header sent, PHP error handle     2012-11-17 08:45:22

  An easy way to log client side information to server

JavaScript debug is a very troublesome thing in web application development. Because many web browsers will not notify you if there is any error in the JavaScript codes you write. They just silently fail and block the following codes execution. In order to debug JavaScript codes, we need a good log mechanism which will help us log the error information,, we often need to log errors in JavaScript codes to server for debug purpose in a production web application, What should we do? The first ...

   JavaScript log, Ajax,Image,Debug     2012-12-30 09:16:50

  Custom C++ exception class creation

In standard C++, we can use try catch to catch and exception when something goes wrong. These are some built in exception support in C++. By including the #include , we can now catch exceptions in C++ programs. This actually helps us on debugging our code and reduce the maintenance work.However sometimes if we want to create our own custom exception class. What should we do?We should include the #include line and then extend the exception class and implement some methods as you like. The genera...

   C++,std,exception,custom exception,implementation     2012-03-04 09:58:18

  Resolving SVN error "Error validating server certificate for..."

When using SVN to connect secure server, the server needs to send its certificate to the client for verification. In some cases, the certificate sent by the server is not a trusted certificate, the client may choose to trust the certificate if the server is target server for sure.  But users may get "Error validating server certificate for 'https://...'" the next time when they try to connect to the same secure server even if they specified "p" the first time when they are prompted to accep...

   SSL,SVN,SVN.SSL.SERVER     2016-06-27 07:36:49

  Mastering Async/Await in JavaScript: A Comprehensive Guide with Examples

As a veteran JavaScript developer, I have seen the evolution of JavaScript's asynchronous programming landscape. From callbacks to promises and now async/await, JavaScript has come a long way in making it easier to handle asynchronous operations in a clean and readable manner. In this article, we will delve into the world of async/await and explore why it has become a popular choice for handling asynchronous operations in JavaScript. We will cover the basics of async/await, its syntax, and how i...

   JAVASCRIPT,COMPARISON,PROMISE,ASYNC AWAIT     2023-02-12 07:26:15

  Restore mocked variables in GoLang unit test

One of the guarding principles of writing unit test is that there should be no real external calls for dependant services. Unit test should run by its own and can run without issues on any environment including local, build, test environment. This indicates there should be some mock responses whenever an external call is needed so that different unit test scenarios can be covered. How can this be done in GoLang? In GoLang, anything can be assigned to a variable even including functions. A variab...

   GOLANG,UNIT TEST,MOCK FUNCTION,RESTORE MOCK     2021-12-10 20:43:00

  Fix could not read Username for 'https://xxx.com': terminal prompts disabled

Recently was working on a project which needed to build a docker image, but unfortunately it kept failing as below error was seen. fatal: could not read Username for 'https://xxx.com': terminal prompts disabled Based on the error, it looked like it was trying to pull code from remote Gitlab repository but failed as the terminal prompt is disabled. At first glance, have a doubt why it needs terminal prompt to be enabled? It should just succeed and without prompting for anything. The only reason...

   GIT,TERMINAL PROMPTS DISABLED,DOCKER     2020-12-13 04:43:12