Class must always be instantiated with `new`

[Deewarz]

Summary

Currently, when you declare a class, you can call it as a function:

// C++
v8pp::class_<MyClass> MyClass_class(isolate);
MyClass_class.ctor<const FunctionCallbackInfo<Value>&>();

// JS
const test1 = new addon.MyClass(10); // right way to do
const test2 = addon.MyClass(10); // currently working, wrongly

test2 asssignation should cause an error:

Uncaught TypeError: Class constructor MyClass cannot be invoked without 'new'

attempting to "call" a class without new will result in an error.

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Using_classes#constructing_a_class

Possible solution

You can use IsConstructCall on v8::FunctionCallbackInfo to check if the class is instanciated with new here:

v8pp/v8pp/class.hpp

Lines 225 to 228 in 5759d79

	class_info_.set_ctor([create = std::move(create)](v8::FunctionCallbackInfo<v8::Value> const& args)
	{
	return create(args);
	});

if(!args.IsConstructCall()) {
    //  Throw type error: Uncaught TypeError: Class constructor %s cannot be invoked without 'new'
    return;
}