Go language custom package builds your own programming tool library

Part 1: Custom package basics

1.1 Defining the package interface

Before creating a custom package, we need to clarify the interface of the package, i.e. what functions the package provides.

For example, you can create a package that handles strings.

// Interface definition of stringutil packagepackage stringutil
// Reverse function inverts the stringfunc Reverse(s string) string {
    // ...
    return reversedString
}

1.2 Internal implementation

Next, implement the package's functions. In the stringutil package, the Reverse function is implemented.

// The internal implementation of stringutil packagepackage stringutil
// Reverse function inverts the stringfunc Reverse(s string) string {
    // ...
    return reversedString
}

1.3 Initialization function

If the package needs to perform some initialization operations when in use, you can define an initialization function (init function).

// Initialization function of stringutil packagepackage stringutil
import "fmt"
func init() {
    ("Stringutil package has been initialized")
}

Part 2: Dependency Management

When creating custom packages, you usually rely on other third-party packages. Go language uses go mod to manage package dependencies.

# Initialize go modgo mod init mypackage
# Add dependency packagego get /example/package

Part 3: Using Custom Packages

When the package's interface and implementation are completed, this custom package can be introduced and used in other programs.

// 
package main
import (
    "fmt"
    "mypackage/stringutil"
)
func main() {
    input := "Hello, World!"
    reversed := (input)
    ("Reversed String:", reversed)
}

Part 4: Custom package cases

4.1 Create a custom log package

// The interface definition of the logger packagepackage logger
import "fmt"
// The Log function outputs the log to the consolefunc Log(message string) {
    ("Log:", message)
}

// Internal implementation of logger package</code>&lt;code&gt;package logger&lt;/code&gt;
&lt;code&gt;import "time"&lt;/code&gt;
&lt;code&gt;func init() {&lt;/code&gt;&lt;code&gt;    Log("Logger is initialized")&lt;/code&gt;&lt;code&gt;}&lt;/code&gt;
&lt;code&gt;// Log Function outputs logs to console，With a time stamp&lt;/code&gt;&lt;code&gt;func Log(message string) {&lt;/code&gt;&lt;code&gt;    timestamp := ().Format("2006-01-02 15:04:05")&lt;/code&gt;&lt;code&gt;    ("[%s] %s\n", timestamp, message)&lt;/code&gt;&lt;code&gt;}

4.2 Using custom log packages in the main program

// The internal implementation of the logger packagepackage logger
import "time"
func init() {
    Log("Logger is initialized")
}
// The Log function outputs the log to the console with a time stampfunc Log(message string) {
    timestamp := ().Format("2006-01-02 15:04:05")
    ("[%s] %s\n", timestamp, message)
}

Part 5: Packaging and Publishing

The custom package is stable and after testing, it can be packaged into a library for other developers to use. You can use the go build command to build custom packages.

# Execute the following command in the custom package directorygo build

Part 6: Best Practices for Custom Packages

6.1 Naming Specifications

The naming of custom packages should be descriptive and follow the naming specifications of the Go language, and try to avoid using single-character package names.

6.2 Documentation and sample code

Write clear documentation for custom packages and provide detailed sample code to facilitate other developers to understand and use your package.

Summarize

Custom packages are a very important part of the Go language, providing an effective way to organize and manage code to help developers build more modular and maintainable applications.

I hope that through the study of this article, developers can use custom packages more proficiently and flexibly apply them in actual projects to improve the reusability and readability of the code.

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