Vergilius

A Guide to the Hell Called 'your code'.

About

Vergilius is a helper class that allows the executed code to determine its position in the file, the name of the currently executing function, and similar information.

This class has no practical use other than the ability to annoy coworkers with a "works on my machine" (refer to the example).

How does it work?

By using a stack trace.

Instalation

Currently, Vergilius only support the web version.

Web

<script src="https://kawyn.github.io/vergilius/lib/main.min.js"></script>

Node.js

Currently, Vergilius can't be downloaded via npm, so for local usage, download the main.js from the lib directory and integrate it into your project manually.

Examples

The functions in the library are named after Dante's Divine Comedy. However, if someone dislikes the fancy names, they can use the boring aliases listed in the table.

Function name

function foo() { 
    
    console.log(Vergilius.canto); 
}

function bar() {

    console.log(Vergilius.canto);
}

foo(); // prints 'foo'
bar(); // prints 'bar'

Different behaviors for the same function

Thanks to the ability to retrieve the names of previously visited functions (Vergilius.cantos), it is possible to define different behaviors for the same function.

function foo() { 
    
    console.log(multiply(10, 10)); // prints '20'
}

function bar() {

    console.log(multiply(10, 10)); // prints '100'
}

function multiply(a, b) { 

    if (Vergilius.cantos[1] === `foo`)
        return a + b;

    return a * b;
}

This idea can be extended so that all functions in the file your coworker is working on do something other than what they should.

// don_quixote's_file.js
function foo() { 
    
    console.log(multiply(10, 10)); // prints '20'
}

// your_file.js
function bar() {

    console.log(multiply(10, 10)); // prints '100'
}

function multiply(a, b) { 

    if (Vergilius.circles[1] === `don_quixote's_file.js`)
        return a + b;

    return a * b;
}

Private methods

Additionally, thanks to this library, it is possible to define private functions in classes (as if it wasn’t already possible using #).

class Limbo {


    foo() { 
        
        this.bar();
    }

    bar() {

        const inferno = Vergilius.inferno;

        if (inferno[1].class != this.constructor.name)
            throw `${Vergilius.canto} is a private function. Only ${this.constructor.name} members can access it.`;

        console.log('bar');
    }
}

const limbo = new Limbo();

limbo.foo(); // prints 'bar';
limbo.bar(); // throws error

Generator of all sequences consisting of the letters 'a' and 'b' of length 4

An attempt to create something useful using this library.

function a() {

    if (Vergilius.cantos.length > 4) {
    
        console.log(Vergilius.cantos.splice(0, 4).join(''));
        return;
    }

    a();
    b();
}

function b() {

    if (Vergilius.cantos.length > 4) {
       
        console.log(Vergilius.cantos.splice(0, 4).join(''));
        return;
    }

    a();
    b();
}


a();
b();

Properties

Property	Alias	Returns	Description
row	-	Number	The row number in the file where the code is executed.
column	-	Number	The column number in the file where the code is executed.
canto	function	String	The name of the currently executing function.
cantos	functions	String[]	A list of previously visited functions (includes current).
circle	file	String	The file name where the code is executed.
circles	files	String[]	A list of file names from the call stack.
inferno	data	Object[]	A detailed parsed stack trace containing function names, file names, row, and column numbers.