Scope transpiled class attributes in a function instead of an object

[AlexECX]

Change Summary

Currently, the transpiled attributes of a class are scoped in an object as key/value pairs. This is problematic when trying to handle class scoped operation, for example:

classA:
print("hello from A")
A=1B=A+1

The main objective of this PR is to facilitate the implementation of class scoped operations.

Secondary changes:

• Add support for class variable operations.
• Add support for class scoped expressions.
• Handle 'assignationless' annotated class variable.

Related issue number

Related to #630 and #663.

PR Checklist

• Adapted tests
• Passes tests
• Documented changes
• Compatibility with __iter__
• Compatibility with __next__
• Compatibility with dataclass class decorator
• Compatibility with user and built-in decorators
• Compatibility with nested classes

Sample before/after

Python source:

classA:
print("hello from A")
z: stra: str=""b=1c=b+1def__iter__(self):
returniter([1])
def__next__(self):
returnnext(iter([1]))
deffunc(self, arg):
returnarg@decordefdecorated_func(self, arg):
returnarg@staticmethoddefstatic_func(arg):
returnarg@classmethoddefclassmethod_func(cls, arg):
returnarg@propertydefproperty_func(self):
return1

Before:

exportvarA=__class__('A',[object],{__module__: __name__,// no print()// z: str causes an error at transpile timea: '',b: 1,c: b+1,// causes an error at JS runtimeget__iter__(){return__get__(this,function(self){returnpy_iter([1]);});},[Symbol.iterator](){returnthis.__iter__()},get__next__(){return__get__(this,function(self){returnpy_next(py_iter([1]));});},next: __jsUsePyNext__,getfunc(){return__get__(this,function(self,arg){returnarg;});},getdecorated_func(){return__get__(this,decor(function(self,arg){returnarg;}));},getstatic_func(){returnfunction(arg){returnarg;};},getclassmethod_func(){return__getcm__(this,function(cls,arg){returnarg;});},get_get_property_func(){return__get__(this,function(self){return1;});}});Object.defineProperty(A,'property_func',property.call(A,A._get_property_func));;

After:

exportvarA=__class__('A',[object],(()=>{letcls={};cls.__module__=__name__;print("hello from A");varz=cls.z;vara=cls.a='';varb=cls.b=1;varc=cls.c=b+1;__def__(cls,function__iter__(){return__get__(this,function(self){returnpy_iter([1]);});});cls[Symbol.iterator]=()=>cls.__iter__();__def__(cls,function__next__(){return__get__(this,function(self){returnpy_next(py_iter([1]));});});cls.next=__jsUsePyNext__;__def__(cls,functionfunc(){return__get__(this,function(self,arg){returnarg;});});__def__(cls,functiondecorated_func(){return__get__(this,decor(function(self,arg){returnarg;}));});__def__(cls,functionstatic_func(){returnfunction(arg){returnarg;};});__def__(cls,functionclassmethod_func(){return__getcm__(this,function(cls,arg){returnarg;});});__def__(cls,function_get_property_func(){return__get__(this,function(self){return1;});});returncls;})());Object.defineProperty(A,'property_func',property.call(A,A._get_property_func));;

[faerot]

It creates major problems like creating unnecessary scope when class attributes will overshadow global variables with the same name. If you have global name a and want to use it inside method, you will access var a in this class function instead.

[AlexECX]

I haven't been able to work on this, and probably won't unless I take a deeper dive into compiler.py.

Given:

class A:
z: str
a: str = ""
b = 1
c = b + 1

need a way to get

export var A = __class__ ('A', [object], (() => {
let cls = {};
cls.__module__ = __name__;
cls.z = undefined;
cls.a = '';
cls.b = 1;
cls.c = cls.b + 1;
};

instead of my current

export var A = __class__ ('A', [object], (() => {
let cls = {};
cls.__module__ = __name__;
var z = cls.z;
var a = cls.a = '';
var b = cls.b = 1;
var c = cls.c = b + 1;
};

the difficult part being to replace cls.c = b + 1 by cls.c = cls.b + 1.