Category Golang

Golang Tips & Tricks #6 - the _test package

Testing is one of the hardest stuff in programming. Today trick will help you organize your tests and the production code. Let’s assume you have a package called orders. When you want to separate the package for tests from the production code you can create a new folder and write tests there. It will work but there’s a more clearer way - put your tests to the folder with you package but suffix the package’s name in tests with _test.

Golang Tips & Tricks #5 - blank identifier in structs

While working with structures, there’s a possibility to initialize the structure without providing the keys of fields. type SomeSturct struct { FirstField string SecondField bool } // ... myStruct := SomeSturct{"", false} If we want to force other (or even ourselfs) to explicitly providing the keys, we can add _ struct{} in the end of the structure. type SomeSturct struct { FirstField string SecondField bool _ struct{} } // COMPILATION ERROR myStruct := SomeSturct{"", false} The code above will produce too few values in SomeSturct literal error.

Golang Tips & Tricks #4 - internal folders

While developing a library, we create a directory structure to keep the code organized. However, some exported functions or struct should not be used by users of the library. The achieve that, call the package internal. . ├── bar │ ├── bar.go │ └── internal │ └── foobar.go ├── internal │ └── foo.go └── main.go In the example above, the foo.go can be included only in the main.go. What’s more, only the bar.

Golang Tips & Tricks #3 - graceful shutdown

In the microservices’ world, one thing what’s worth considering is a graceful shutdown. This is important to not lose data while shutting down a container. The container orchestrator like Kubernetes can restart the container by sending SIGTERM or SIGINT signal. Those signals can be handled to safely close all connections and finish background tasks. Signals are propagated using os.Signal channel. You can add the above code to your main. var gracefulStop = make(chan os.

Golang Tips & Tricks #2 - interfaces

When it comes to interfaces, a good practice is to create an interface where you’ll use it. Creating interfaces in advanced is not recommended in Go. There are two exceptions: you’re creating a library which will be used in different projects you’ll have more than 1 implementation In the example below, we have a storage implementation. type inMemoryStorage struct { mutex *sync.Mutex storage map[string]*Value } func NewStorage() *inMemoryStorage { return &inMemoryStorage{ storage: map[string]*Value{}, mutex: &sync.

Golang Tips & Tricks #1 - errors

You should use the package instead of errors package for errors in your applications. The default package lacks a few things like: stack trace easy appending message to the error and more It helps with debugging a lot. Below you can find an example error message with the stack trace. An important thing to remember is that you should wrap every error which is from any external library or your freshly created error you want to return.


Go deeper – Database connection pool

Golang uses a connection pool to manage opened connections for us. As a result, new connections are used when no free connection left and reuses them when golang finds an idle connection. The most important thing is that when two queries are called one by one it does not mean that the queries will use the same connection. It may be true if not in every case. In the example below, you can find two queries which may seem to be executed in one connection.

Be aware of copying in Go

Some bugs are very hard to find and to reproduce but easy to fix. To avoid them, it’s helpful to know how the tools we’re using work under the hood. From this article, you’ll learn what shallow and deep copy are and which errors you can avoid thank’s the knowledge about them. Can you find a problem with the code below? q1 := NewQuestion(1, "How to be cool?") q1 = q1.

How to send multiple variables via channel in golang?

Channels in golang are referenced type. It means that they are references to a place in the memory. The information can be used to achieve the goal. Firstly, let’s consider using structs as the information carrier. This is the most intuitive choice for the purpose. Below you can find an example of a struct which will be used today. type FuncResult struct { Err error Result int } func NewFuncResult(result int) FuncResult { return FuncResult{Result: result} } The idea is to create a channel from the struct, pass the channel to a function and wait for the result.