Module LensStudio:Subprocess

Example

// module.json
{
    "main": "main.js",
    "permissions": ["subprocess"]
}
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// main.js

import { CoreService } from 'LensStudio:CoreService';
import * as sb from 'LensStudio:Subprocess';

////////////////////////////////////////////////////////////////////////////////////////////////////
// Helpers that print out some passed in text with some prefix 
// that will be included with every print out.
////////////////////////////////////////////////////////////////////////////////////////////////////

function createStartedCallback(text) {
    return function () {
        console.log('Process: ' + text + ' started');
    };
}

function createStateChangedCallback(text) {
    return function (state) {
        console.log('Process: ' + text + ' state changed to: ' + state);
    };
}

function createErrorCallback(text) {
    return function (errorType) {
        console.log('Process: ' + text + ' encountered process error of type: ' + errorType);
    };
}

function createExitCallback(text) {
    return function (exitCode) {
        console.log('Process: ' + text + ' exited with code ' + exitCode);
    };
}

function createStdOutCallback(text) {
    return function (data) {
        console.log('Process: ' + text + ' stdout: ' + data);
    };
}

function createStdErrCallback(text) {
    return function (data) {
        console.log('Process: ' + text + ' stderr: ' + data);
    }   
}

////////////////////////////////////////////////////////////////////////////////////////////////////
// Core Plugin that gets Python3 Version and Git Status on this plugin's folder. 
////////////////////////////////////////////////////////////////////////////////////////////////////
export class ProcessTest extends CoreService {
    static descriptor() {
        return {
            id: 'snap.test.SubprocessExample',
            interfaces: CoreService. descriptor().interfaces,
            name: 'Subprocess Example',
            description: 'Run some sync and async subprocess.',
            dependencies: []
        };
    }

    constructor(pluginSystem) {
        super(pluginSystem);
    }

    _subprocessPythonVersion() {
        // Store subprocess in `this` so we can kill it when the plugin closes
        this.pythonVersionSubprocess = sb.Subprocess.create('python3', ['--version'], {});
        
        // Hook into subprocess
        const myCommand = this.pythonVersionSubprocess.command;
        this.connections.push(this.pythonVersionSubprocess.started.connect(createStartedCallback(myCommand)));
        this.connections.push(this.pythonVersionSubprocess.stateChanged.connect(createStateChangedCallback(myCommand)));
        this.connections.push(this.pythonVersionSubprocess.errored.connect(createErrorCallback(myCommand)));
        this.connections.push(this.pythonVersionSubprocess.exited.connect(createExitCallback(myCommand)));
        this.connections.push(this.pythonVersionSubprocess.stdout.connect(createStdOutCallback(myCommand)));
        this.connections.push(this.pythonVersionSubprocess.stderr.connect(createStdErrCallback(myCommand)));

        // Start the process
        this.pythonVersionSubprocess.start();

        // Write to stdin
        for (let i = 0; i < 5; i++) {
            this.pythonVersionSubprocess.stdin.writeString('Hello, world: ' + i + '\n');
            sb.spawnSync('sleep', ['1'], {});
        }
    }

    _subprocessSyncGitStatus() {
        const pluginFolder = import.meta.resolve(".");
        const options = {
            cwd: new Editor.Path(pluginFolder)
        }

        const result = sb.spawnSync('git', ['status'], options);

        console.log('success: ' + result.success);
        console.log('stdout: ' + result.stdout);
        console.log('stderr: ' + result.stderr);
        console.log('exitCode: ' + result.exitCode);
    }

    start() {
        this.connections = [];

        console.log("Start: subprocess for Git Status ------------------------------");
        this._subprocessSyncGitStatus();
        console.log("Done: subprocess for Git Status -------------------------------");
        
        console.log("Start: subprocess for Python3 Version -------------------------");
        this._subprocessPythonVersion();
    }

    stop() {
        // Need to kill the asynchronus process we started in `subprocessPythonVersion`.
        // For example when the app closes, or user disables the plugin.
        this.pythonVersionSubprocess.kill();
        console.log("Done: subprocess for Python3 Version --------------------------");
    }
}
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