How to import packages in Go language and matters needing attention

Title: How to import packages in Go language and precautions

Go language is an open source statically typed programming language, developed by Google, mainly used for building High-performance web services and distributed systems. In the Go language, package import is a very important operation, which can help us organize code and reuse modular functions. This article will introduce how to import packages in Go language and some matters needing attention, and provide specific code examples.

1. How to import packages

In Go language, to use functions or types in other packages, you first need to import them into the current source file . The package import syntax in Go language is as follows:

import "包的路径"

Among them, the path of the package can be a local path (relative path or absolute path) or a remote path (such as github.com, etc.). When using a package, you can specify an alias to simplify the reference of the package, for example:

import fm "fmt"

In this way, you can use the alias fm directly when using functions in the fmt package. Additionally, when importing multiple packages, you can use parentheses to wrap them. For example:

import (
    "fmt"
    "math/rand"
)

2. Precautions for the package

When using the package, you need to follow some precautions to ensure the normal operation and maintenance of the code:

• The package name and import path must be consistent with the actual folder and file name. There can only be one package name in a folder, and the package name can be different from the folder name.
• Only imported packages will be compiled into executable files, unused packages will not be compiled into executable files.
• There is no global namespace in the Go language. The variables and functions inside the package are private by default (that is, they are only visible within the package). If you want to use them in other packages, you need to capitalize the first letter of their names.
• Avoid circular import, that is, package A imports package B, and package B imports package A. This situation will lead to compilation errors.

3. Code example

Below we use a simple example to demonstrate the import and use of the package:

Assume we have two files, in the same folder:

1. calc.go:

package calc

func Add(a, b int) int {
    return a + b
}

2. main.go:

package main

import (
    "fmt"
    "yourfoldername/calc"
)

func main() {
    sum := calc.Add(10, 20)
    fmt.Println("Sum is:", sum)
}

In this example, calc.go# is imported from the main.go file via import "yourfoldername/calc" Add function in the file, and successfully call it to calculate the result and print it.

Through the introduction of this article, I believe readers will have a deeper understanding of the import methods and precautions for packages in the Go language. Reasonable use of packages can help us better organize code, improve code reusability, and avoid some common mistakes. It is hoped that readers can flexibly use package import when writing Go language programs, and pay attention to abide by relevant conventions and specifications.

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