JS’s classes cannot be used correctly in python #170

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1. wiwichips commented on Sep 14, 2023

   

   wiwichips

   on Sep 14, 2023

   Last edited by wiwichips

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   Hi @zanxueyan , thank you so much for taking the time to play with PythonMonkey and submit this issue!

   Since Python lacks a new keyword for instantiating objects, we had to add a new(class) function to the PythonMonkey API. Here's a small example:

   import pythonmonkey as pm
   jsDateClass = pm.Date
   myDate = pm.new(jsDateClass)(0) # in js this would be: let myDate = new Date(0);

   ---

   Here's the change you would need to make to get your code working

   //JS code
   class Runoob {
     constructor(name, url) {
       this.name = name;
       this.url = url;
     }
     setname(name)
     {
         this.name = name;
         console.log("box");
         return this.name;
     }
   }
   //first Type:transmit the class
   module.exports = Runoob
   
   //secend Type: Create an instance pass an instance
   pepole = new Runoob("ddd","www.baidu.com")

   #python code
   
   
   import pythonmonkey as pm
   
   Runoob =pm.require("./pyreadjs")
   #first Type Error:TypeError: class constructors must be invoked with 'new'
   
   pep = pm.new(Runoob)("ddd","www.baidu.com")
   # but can't code like this:
   #test = new pep("ddd","www.baidu.com")
   
   print(pep.setname("test")) #can return OK
   print(pep.name)     #NOT CHANGE

   Running the python program results in the following output:

   box
   test
   ddd
   

   I changed a couple things in your python code here:

   1. Runoob = pm.require("./pyreadjs")

   • Get the JS class from pyreadjs.js

   2. pep = pm.new(Runoob)("ddd","www.baidu.com")

   • Instantiate a new Runoob and set a variable pep equal to it. I'm using the pm.new(Class)(args...) function to instantiate a new object

   ---

   I'm sorry you had this experience, we'll try to improve the error message or improve the documentation so more people don't run into this in the future. Thank you!!!
2. wiwichips

   closed this as completedon Sep 14, 2023
3. zanxueyan commented on Sep 19, 2023

   

   zanxueyan

   on Sep 19, 2023

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   Thanks a lot！
4. zanxueyan commented on Sep 27, 2023

   

   zanxueyan

   on Sep 27, 2023

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   `import pythonmonkey as pm

   Runoob = pm.require("./pyreadjs") # Get the JS class from pyreadjs.js

   pep = pm.new(Runoob)("ddd", "www.baidu.com") # Instantiated object
   print(pep.add(2, 3))
   pep.setname("test")
   print(pep.name) # You cannot get the value of the property directly in this way
   ##Whether you can support getting its value from an attribute???

   print(pep.getname()) # You need to use the built-in function to get the value`
5. wiwichips commented on Sep 28, 2023

   

   wiwichips

   on Sep 28, 2023

   Last edited by wiwichips

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   Hi @zanxueyan Good catch!!! - you're right, something is wrong here...

   import pythonmonkey as pm
   
   Runoob = pm.require("./pyreadjs") # Get the JS class from pyreadjs.js
   
   pep = pm.new(Runoob)("Will Pringle", "www.google.com") # Instantiated object
   pep.setname("Joseph")
   
   print(pep['name'])   # prints Will Pringle BUT SHOULD PRINT Joseph
   print(pep.name)      # prints Will Pringle BUT SHOULD PRINT Joseph
   print(pep.getname()) # prints Joseph

   I'll file a bug report - thank you so much for finding and reporting this error!

   👍React with 👍1Reacted by zanxueyan
6. wiwichips commented on Sep 28, 2023

   

   wiwichips

   on Sep 28, 2023

   Last edited by wiwichips

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   @zanxueyan check this out: #172 (comment)

   seems to be another side effect of this bug - I'll notify you when we have it patched

   ---

   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"!!!

   prints

   Joe
   Will
   Will
   Joe
   Liang
   Liang
   
   
7. zanxueyan commented on Nov 6, 2023

   

   zanxueyan

   on Nov 6, 2023

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   @wiwichips Thank you very much! Are there any further optimization results at present? Looking forward to...
8. wiwichips commented on Jan 31, 2024

   

   wiwichips

   on Jan 31, 2024

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   This should be solved in the next release of PythonMonkey - not sure when that is - but I'll make sure to notify you @ zanxueyan

   👍React with 👍1Reacted by zanxueyan