Go language learning [1] Preparations before basic grammar

What is cloud native

The ability to build and run large-scale applications in dynamic environments including public cloud, private cloud, hybrid cloud, etc.

• Cloud native is an idea and a collection of technologies and enterprise management methods.
• Technology Level
• Applications are designed from the ground up to run on the cloud.
• Cloud platform is based on automation system.
• Process level
• Based on DevOps, CI/CD

Based on multiple means
• Application containerization encapsulation;
• Service mesh;
• Immutable infrastructure;
• Declarative API.

The significance of cloud native
• Improves system adaptability, manageability, and observability;
• Enables engineers to make frequent and predictable system changes at minimal cost.
• Improve speed and efficiency, help business growth, and shorten I2M (Idea to Market)

study method

IDE configuration of go language VScode

I don’t use goland because I don’t have money for the time being + I don’t want to use piracy for the time being + I don’t want to add a few gigabytes of storage consumption to the computer for the time being + I am also using vscode to learn the Rust language.

There are many online tutorials here, so I won’t list them all. Here is a recommended environment configuration for developing Go language under [Golang] VsCode (super detailed explanation with pictures and texts)

Perfectly solved my trouble of running code with vscode.

Things to pay attention to when writing go code

• You must indicate which package this file belongs to on the first non-commented line in the source file. [Package main represents an independently executable program. Each Go application contains a package named main. 】
• The fmt package implements functions for formatted IO (input/output)
• func main() is the function where program execution begins. The main function must be included in every executable program. Generally speaking, it is the first function to be executed after startup (if there is an init() function, this function will be executed first).
• / ... / is a single-line comment starting with //; multi-line comments are also called block comments, which start with /* and end with */, and cannot be nested. Multi-line comments are generally used in package documentation. Describe or comment code snippets into blocks
• When identifiers (including constants, variables, types, function names, structure fields, etc.) start with an uppercase letter, such as: Group1, then objects using this form of identifier can be used by the code of the external package (client The end program needs to import the package first), which is called an export (like public in an object-oriented language); if identifiers start with a lowercase letter, they are not visible outside the package, but they are visible inside the entire package And available (like protected in object-oriented languages)
• The Go language does not support dynamic linking , so all dependencies will be compiled into the same binary file during compilation.

some basic commands

bug

start a bug report

build

compile packages and dependencies

clean

remove object files and cached files

doc

show documentation for package or symbol

env

print Go environment information

fix

update packages to use new APIs

fmt

gofmt (reformat) package sources

generate

generate Go files by processing source

get

add dependencies to current module and install them

install

compile and install packages and dependencies

list

list packages or modules

mod

module maintenance

run

compile and run Go program

test

test packages

tool

run specified go tool

version

print Go version

vet

report likely mistakes in packages

Specify the output directory.
go build –o bin/mybinary.Common
environment variable settings are compiled for the operating system and CPU architecture.
GOOS=linux GOARCH=amd64 go build
Full support list.

 $GOROOT/src/go/build/syslist.go

basic grammar

Here are the novice tutorials recommended .

Go language comes with native tests

import "testing"
func TestIncrease(t *testing.T) {
    
    
t.Log("Start testing")
increase(1, 2)
}

go test ./… -vRun tests

The go test command scans all *_test.gofiles ending with . The convention is to put the test code and the official code in the same directory .
For example, the test code of foo.go is generally written in foo_test.go

Go vet

Code static inspection to find possible bugs or suspicious constructs.

Print-format error, check for type mismatched print

str := “hello world!”
fmt.Printf("%d\n", str)

Boolean errors, check for expressions that are always true, false or redundant

fmt.Println(i != 0 || i != 1)

Range loop, for example, the main coroutine in the following code will exit first, and the go routine cannot be executed.

words := []string{
    
    "foo", "bar", "baz"} 
for _, word := range words {
    
    
go func() {
    
    
	fmt.Println(word). 
	}()
}

Unreachable code, such as the code after return

Other errors, such as variable self-assignment, error check lag, etc.

res, err := http.Get("https://www.spreadsheetdb.io/") 
defer res.Body.Close() 
if err != nil {
    
    
	log.Fatal(err)
}

Code version control

fmt.Println(…) and fmt.Print()

You can output a string to the console and automatically add a newline character \n at the end.

The two functions Print and Println also support the use of variables, such as: fmt.Println(arr). If not specified otherwise, they print the variable arr to the console in the default printing format.

Development steps

Directory Structure