JavaCPP Presets for CPython

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By downloading these archives, you agree to the terms and conditions for accessing or otherwise using Python.

Introduction

This directory contains the JavaCPP Presets module for:

• CPython 3.10.8 https://www.python.org/

Please refer to the parent README.md file for more detailed information about the JavaCPP Presets.

Documentation

Java API documentation is available here:

• http://bytedeco.org/javacpp-presets/cpython/apidocs/

∗ Call Py_Initialize(cachePackages()) instead of just Py_Initialize().
∗ To satisfy OpenSSL, we might need to set the SSL_CERT_FILE environment variable to the full path of cacert.pem extracted by default under ~/.javacpp/cache/.

Sample Usage

Here is a simple example of CPython ported to Java from this C source file:

• https://docs.python.org/3/extending/embedding.html#very-high-level-embedding

We can use Maven 3 to download and install automatically all the class files as well as the native binaries. To run this sample code, after creating the pom.xml and Simple.java source files below, simply execute on the command line:

 $ mvn compile exec:java

The pom.xml build file

<project>
    <modelVersion>4.0.0</modelVersion>
    <groupId>org.bytedeco.cpython</groupId>
    <artifactId>simple</artifactId>
    <version>1.5.8</version>
    <properties>
        <exec.mainClass>Simple</exec.mainClass>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.bytedeco</groupId>
            <artifactId>cpython-platform</artifactId>
            <version>3.10.8-1.5.8</version>
        </dependency>
    </dependencies>
    <build>
        <sourceDirectory>.</sourceDirectory>
    </build>
</project>

The Simple.java source file

import org.bytedeco.javacpp.*;
import org.bytedeco.cpython.*;
import static org.bytedeco.cpython.global.python.*;

public class Simple {
    public static void main(String[] args) throws Exception {
        Pointer program = Py_DecodeLocale(Simple.class.getSimpleName(), null);
        if (program == null) {
            System.err.println("Fatal error: cannot decode class name");
            System.exit(1);
        }
        Py_SetProgramName(program);  /* optional but recommended */
        Py_Initialize(cachePackages());
        PyRun_SimpleString("from time import time,ctime\n"
                         + "print('Today is', ctime(time()))\n");
        if (Py_FinalizeEx() < 0) {
            System.exit(120);
        }
        PyMem_RawFree(program);
        System.exit(0);
    }
}