How to use python in golang

Golang and Python are two very popular programming languages, both of which have a wide range of application scenarios. In some cases, we need to use these two languages ​​​​to complete certain tasks together, so how to use Python to assist Golang programming? This article will explain in detail how Golang uses Python.

1. Why do you need to use Python to assist Golang programming?

In the Golang development process, sometimes you need to use Python to handle certain tasks, such as data analysis, machine learning, and web crawlers. wait. Although these tasks can also be completed in Golang, Python is more widely used and more mature in these areas, so using Python can complete these tasks faster and more conveniently.

2. How golang calls python programs

In Golang, we can execute Python programs through the Exec function in the os package. The sample code is as follows:

package main

import (
    "fmt"
    "os/exec"
)

func main() {
    cmd := exec.Command("python", "test.py", "arg1", "arg2")
    out, err := cmd.CombinedOutput()
    if err != nil {
        fmt.Println(err)
    }
    fmt.Println(string(out))
}

The above code , we use the Command function in the exec package to create a command to execute the Python program. Among them, the first parameter is the name of the program to be executed, and the second parameter is the parameter passed to the program. In this example, we are executing the test.py program and passing in the two parameters arg1 and arg2.

Use the CombinedOutput method to start the command and execute the program. The return value is the output result of the program and the error message during execution. If an error occurs, the err variable is assigned a value, otherwise the out variable contains the output of the program.

The Python script test.py is used in the sample code. In the following chapters, we will explain in detail how to write Python programs.

3. How Python interacts with Golang

In addition to executing Python programs through the command line, we can also interact with Golang through Python's standard library. Python provides some modules, such as ctypes and cffi, to call Golang's C language interface in Python to achieve communication between the two.

The following is a simple sample code that demonstrates how to call a Golang function in Python and return the result:

1. Write the Golang function in the main.go file

package main

import "C"

// 导出函数
//export SayHello
func SayHello(name *C.char) *C.char {
    return C.CString("Hello, " + C.GoString(name) + "!")
}

func main() {}

In Golang, we define a SayHello function, which receives a string parameter and returns a string, which uses the C.CString and C.GoString functions of the CGo language for type conversion.

2. Write a program that calls Golang functions in python

import ctypes

lib = ctypes.cdll.LoadLibrary('./main.so')

# 指定函数返回类型
lib.SayHello.argtypes = [ctypes.c_char_p]
lib.SayHello.restype = ctypes.c_char_p

# 调用函数
result = lib.SayHello(b'World')
print(result.decode())

In Python, we use the ctypes module to load the compiled main.so library and specify SayHello Function parameter types and return value types. Then by calling this function, passing in the string parameter "World", the output result is "Hello, World!".

The above code example demonstrates how to call a Golang function in Python and return the result.

4. How to use Golang code in Python program

We can also use Golang code in Python program and obtain the output result of Golang program. To do this, we need to use the C code interface of the CGo language to encapsulate the Golang function into a C function, and then call the C function through Python's ctypes module.

The following is a simple example code that demonstrates how to use Golang code in Python:

1. Define the Golang function in the main.go file (same as the previous example)

package main

import "C"

// 导出函数
//export SayHello
func SayHello(name *C.char) *C.char {
    return C.CString("Hello, " + C.GoString(name) + "!")
}

func main() {}

2. Declare the Golang function in the main.h file

#ifndef MAIN_H
#define MAIN_H

#ifdef __cplusplus
extern "C" {
#endif

// 声明导出函数
char* SayHello(char*);

#ifdef __cplusplus
}
#endif

#endif

Since the Python module cannot directly reference the Go function, we need to encapsulate and declare the Go function through the C interface .

3. Implement the C interface of the Golang function in the main.c file

#include <stdlib.h>
#include "main.h"

// 使用import来导入Go包
#include "_cgo_export.h"

char* SayHello(char* name) {
    char* result = (char*)malloc(50 * sizeof(char));
    sprintf(result, "%s", SayHelloGo(name));
    return result;
}

In the C code, we implement the C interface of the SayHello function. The _Go_SayHello function is called, which is automatically generated by CGo and can directly call the SayHello function in Go code. It should be noted here that the function generated by CGo is named _Go_ plus the name of the Go function.

4. Compile and generate the corresponding .so file

Execute the following command to generate the corresponding .so file:

$ go build -o main.so -buildmode=c-shared main.go

5. In Python Call the encapsulated C interface

import ctypes

lib = ctypes.cdll.LoadLibrary('./main.so')

# 指定函数返回类型
lib.SayHello.argtypes = [ctypes.c_char_p]
lib.SayHello.restype = ctypes.c_char_p

# 调用函数
result = lib.SayHello(b'World')
print(result.decode())

In Python, we use the ctypes module to load the .so library encapsulated with the C interface, and specify the parameter type and return value type of the SayHello function. Then by calling this function, passing in the string parameter "World", the output result is "Hello, World!".

The above code example demonstrates how to use Golang code in Python.

Summary: The above are the methods and steps for how to use python in golang. By mastering these skills, you can quickly complete complex data processing, web crawlers, machine learning and other tasks, and improve development efficiency.

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