Object methods use incorrect this
#172
Comments
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@zanxueyan ran into a byproduct of this bug described in this message here: #170 (comment) It can be described by this minimal repro: import pythonmonkey as pm
pm.eval("""
class Human {
constructor(name)
{
this.name = name;
}
setName(name)
{
this.name = name;
}
getName()
{
return this.name;
}
}
""")
Human = pm.eval('Human')
person = pm.new(Human)('Will')
# setting it using setName
person.setName('Joe')
print(person.getName()) # prints "Joe"
print(person.name) # prints "Will" but should print "Joe"!!!
print(person['name']) # prints "Will" but should print "Joe"!!!
# now try setting it directly
person.name = "Liang"
print(person.getName()) # prints "Joe"
print(person.name) # prints "Liang"!!!
print(person['name']) # prints "Liang"!!!since |
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I don't think this issue should be closed just yet, as while the specific above minimal repro is no longer an issue, there are still cases where the "wrong" In JS, a function always has However in python, there are both functions and methods as distinct types. Python functions are equivalent to, and have similar behaviour as, JS Functions except that they do not have an equivalent to import types
class MyClass:
def pyMeth(self, arg1, arg2):
print(arg1)
print(arg2)
return self
pyObj = MyClass()
result = pyObj.pyMeth("Hello", "World) # result is pyObj
pyDict1 = {"pyMeth": pyObj.pyMeth}
pyDict2 = {"pyMeth": MyClass.pyMeth}
pyDict3 = {}
pyDict3["pyMeth"] = types.MethodType(MyClass.pyMeth, pyDict3)
print(pyObj.pyMeth) # <bound method MyClass.pyMethod of <pyObj>>
print(pyDict1["pyMeth"]) # <bound method MyClass.pyMethod of <pyObj>> (NOT bound to pyDict1)
print(pyDict2["pyMeth"]) # <function MyClass.pyMeth> (NOT bound to anything)
print(pyDict3["pyMeth"]) # <bound method MyClass.pyMethod of <pyDict3>> (bound to pyDict3)
result = pyDict1["pyMeth"]("Hello", "World") # result is pyObj, NOT pyDict1
# result = pyDict2["pyMeth"]("Hello", "World") # results in "missing 1 required positional argument: 'self'" TypeError
result = pyDict3["pyMeth"]("Hello", "World") # result is pyDict3Importantly there is no such thing as an unbound method in python, a method is bound to an object immediately when it is created, and the only way to get a function bound to another object is to manually create a new method object. Below is an example of the consequences of this for pythonmonkey: import pythonmonkey as pm
pm.eval("""
class Human {
constructor(name)
{
this.name = name;
}
setName(name)
{
this.name = name;
}
getName()
{
return this.name;
}
}
""")
Human = pm.eval('Human')
person = pm.new(Human)('Will')
# setting it using setName
person.setName('Joe')
print(person.getName()) # prints "Joe"
print(person.name) # prints "Joe"
print(person['name']) # prints "Joe"
# now try setting it directly
person.name = "Liang"
print(person.getName()) # prints "Liang"
print(person.name) # prints "Liang"
print(person['name']) # prints "Liang"
pyPerson = { "name": "John", "getName": person.getName, "setName": person.setName}
# setting it using setName
pyPerson["setName"]("Jeremy")
print(pyPerson["getName"]()) # prints "Jeremy"
print(pyPerson["name"]) # prints "John"
# now try setting it directly
pyPerson["name"] = "Claude"
print(pyPerson["getName"]()) # prints "Jeremy"
print(pyPerson["name"]) # prints "Claude"My branch #227 introduces a new type called |
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@caleb-distributive let's make sure the default code resolves the issue listed initially above and the one listed in #58 |
Issue type
Bug
How did you install PythonMonkey?
Installed from pip
OS platform and distribution
Ubuntu 22.04
Python version (
python --version)Python 3.10.12
PythonMonkey version (
pip show pythonmonkey)0.2.1
Bug Description
When calling the method of a class,
thisin the scope of the function is globalThis and not the function'sthisexample.js
main.py
--- When I run
python3 main.pyI get the following output:getAreareturnsnanbecauseglobalThis.w === undefinedandundefined * undefined = NaN,getThisreturns globalThis becausethisis not set to the objectthis.Standalone code to reproduce the issue
Relevant log output or backtrace
{'python': {'pythonMonkey': {'dir': '/home/will/.local/lib/python3.10/site-packages/pythonmonkey', 'isCompilableUnit': <built-in function isCompilableUnit>, 'nodeModules': '/home/will/.local/lib/python3.10/site-packages/pythonmonkey/node_modules'}, 'stdout': {'write': <function <lambda> at 0x7fb456a867a0>, 'read': <function <lambda> at 0x7fb452c42200>}, 'stderr': {'write': <function <lambda> at 0x7fb452d9a7a0>, 'read': <function <lambda> at 0x7fb452c42290>}, 'print': <built-in function print>, 'eval': <built-in function eval>, 'exec': <built-in function exec>, 'getenv': <function getenv at 0x7fb456a73880>, 'paths': ['/home/will/test/pm-bug/getArea', '/usr/lib/python310.zip', '/usr/lib/python3.10', '/usr/lib/python3.10/lib-dynload', '/home/will/.local/lib/python3.10/site-packages', '/usr/local/lib/python3.10/dist-packages', '/usr/lib/python3/dist-packages'], 'exit': <built-in method JSFunctionCallable of tuple object at 0x7fb452a58380>, 'load': <function load at 0x7fb452c424d0>}, 'pmEval': <built-in function eval>, 'bootstrap': {'modules': {'vm': {'runInContext': <built-in method JSFunctionCallable of tuple object at 0x7fb452a58500>}, 'ctx-module': {'makeNodeProgramContext': <built-in method JSFunctionCallable of tuple object at 0x7fb452a58580>, 'CtxModule': <built-in method JSFunctionCallable of tuple object at 0x7fb452a58540>}, 'debug': <built-in method JSFunctionCallable of tuple object at 0x7fb452a584c0>, 'fs': {'constants': {'S_IFDIR': 16384.0}, 'statSync': <built-in method JSFunctionCallable of tuple object at 0x7fb452a585c0>, 'statSync_inner': <function statSync_inner at 0x7fb452c42320>, 'readFileSync': <function readFileSync at 0x7fb452c423b0>, 'existsSync': <function existsSync at 0x7fb452c42440>}}, 'require': <built-in method JSFunctionCallable of tuple object at 0x7fb452a58480>, 'builtinModules': {'debug': <built-in method JSFunctionCallable of tuple object at 0x7fb452a583c0>}}, 'console': {'log': <built-in method JSFunctionCallable of tuple object at 0x7fb452a58640>, 'debug': <built-in method JSFunctionCallable of tuple object at 0x7fb452a58680>, 'info': <built-in method JSFunctionCallable of tuple object at 0x7fb452a586c0>, 'warn': <built-in method JSFunctionCallable of tuple object at 0x7fb452a58700>, 'error': <built-in method JSFunctionCallable of tuple object at 0x7fb452a58740>}, 'atob': <function <lambda> at 0x7fb452a39cf0>, 'btoa': <function <lambda> at 0x7fb452a39e10>, 'Square': <built-in method JSFunctionCallable of tuple object at 0x7fb452a58340>}Additional info if applicable
No response
What branch of PythonMonkey were you developing on? (If applicable)
No response
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