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SEARCH KEYWORD -- GOLANG

  Empty slice vs nil slice in GoLang

In Go, there is a type called slice which is built on top of array. It's a very convenient type when we want to handle a group of data. This post will explain a subtle but tricky difference between empty slice and nil slice. A nil slice is a slice has a length and capacity of zero and has no underlying array. The zero value of slice is nil. If a slice is declared like below, it is a nil slice. package main import "fmt" func main() { var a []string fmt.Println(a == nil) } The output will be t...

   GOLANG,JSON,EMPTY SLICE,NIL SLICE     2018-10-18 09:25:21

  The internals of slice in GoLang

There are 3 components of slice:a) Pointer: Points to the start position of slice in the underlying array;b) length (type is int): the number of the valid elements of the slice;b) capacity (type is int): the total number of slots of the slice. Check the following code: package main import ( "fmt" "unsafe" ) func main() { var s1 []int fmt.Println(unsafe.Sizeof(s1)) } The result is 24 on my 64-bit system (The pointer and int both occupy 8 bytes). In the next example, I will use gdb to poke t...

   GOLANG,SLICE     2019-06-30 02:55:22

  Error handling in GoLang

Error handling is one of the must talked topics for any programming language. The program would be more reliable and stable if errors are handled properly and timely. Each programming language has its own way to handle error, this applies to GoLang as well. This post will discuss more about GoLang's error handling mechanism. Error handling Before talking more about GoLang's error handling, we can see how different programming languages are handling errors. C's error check The most direct way of ...

   GOLANG,ERROR HANDLING,FLUENT INTERFACE     2021-03-06 21:36:08

  Will nil == nil be true in GoLang

There is some interview question may ask whether nil == nil be true in GoLang. Wil it be true. false or compilation error? To know the answer, some knowledge about nil in GoLang needs to be explained first. nil definition According to Go's official documentation, the definition of nil is // nil is a predeclared identifier representing the zero value for a // pointer, channel, func, interface, map, or slice type. var nil Type // Type must be a pointer, channel, func, interface, map, or slice type...

   GOLANG,NIL,NIL EXPLANATION     2021-08-08 02:54:15

  New function signal.NotifyContext in GoLang 1.16

os/signal package in GoLang may not be frequently used but it provides some good features like Shutdown() which can be used to gracefully shutdown a running HTTP server. func (srv *Server) Shutdown(ctx context.Context) error With this function, there is no need to use third party library to gracefully shutdown HTTP server. How is it being used? package main import ( "context" "fmt" "net/http" "os" "os/signal" "time" ) func main() { server := http.Server{ Addr: ":8080", } http.Handl...

   GOLANG,NOTIFYCONTEXT,GRACEFUL SHUTDOWN     2021-06-19 01:07:10

  Introduction to GoLang generics and advanced usage

Generics in Go allow you to write code that can work with multiple types of data, without having to write separate versions of the code for each type. This can make your code more flexible and easier to maintain, as you only need to write and test the code once, rather than maintaining multiple versions. To use generics in Go, you first need to define a type parameter, which is a placeholder for the type that the code will work with. For example, you might define a type parameter called "T" like...

   GOLANG,GENERICS     2022-12-17 05:12:21

  A simple example on implementing progress bar in GoLang

Sometimes when handling a long running process, there would be need to track the progress so that people know something is still running instead of doubting something goes wrong. In this case, a progress bar which indicates the current status and progress would be desired. This post will show an example on how to implement progress bar using GoLang. Let's take a look at the final outcome first before jumping into the implementation detail. The key in the implementation is actually just the \r ...

   TUTORIAL,EXAMPLE,GOLANG,PROGRESS BAR     2020-08-08 23:53:15

  combining dwarf failed: unknown load command 0x80000034 solution in GoLang

In case there is below error encountered while running some go program: combining dwarf failed: unknown load command 0x80000034 This may be due to that you are running go 1.16 on a Mac M! machine. If you go to check go version, it may tell you that you are running an arm version of go. go version go1.16.10 darwin/arm64 In such cases, you can try below methods to workaround the issue. Try to upgrade the go version to 1.17 and run the code again. If this is not an option for you because you have t...

   GO 1.16,0X80000034     2021-11-25 07:11:28

  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

  Run code with multiple files in the same main package in GoLang

To run a GoLang program, there needs to be a main() function defined. In some cases when developing some demo program which has multiple files and just wanna put them in the same main package and this folder is not in GOPATH, how to run the program? Let's say we have following folder structure where the main() function is defined in main.go. If you just run below command, it would fail to start to run the program and gives some error if some struct is defined in other files and being used. PS D...

   EXECUTABLE,GOLANG,MAIN PACKAGE,MULTIPLE FILE     2021-05-15 10:20:10

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