Python: Referring to any created object with init

Am building a program in which i use the constructor method in a class. My method looks like this:

class Myclass:
    population = 0
    def __init__(self, var1, var2, var3):
        Myclass.population +=1
        self.var1 = var1
        self.var2 = var2
        self.var3 = var3
        popFile = open('pop.txt', 'wt')
        popFile.write('population = ' + str(int(Myclass.population)))
        print('blablabla')
        print('again blablabla')
        popFile.close()
        pliada = (var1, var2, var3)
        outFile = open('prog.txt', 'at')
        outFile.write(str(pliada) + '\n')
        outFile.close()

My problem is that in the above

outFile.write(str(pliada) + '\n')

I want to save apart from the tuple, the objects name! What else should I add inside the write() func?

For example when I run the program, i type:

First = Myclass('firstvar','secondvar','thirdvar')

and when i use

print(First)

it only prints the above tuple. When I open prog.txt, again its only the tuple there. How can I refer to each object's name (am constructing) so that instead of saving ('firstvar','secondvar',thirdvar') my program will save First ('firstvar','secondvar',thirdvar'), where First is the var I entered to the program?

Thanks

Solution

At object creation time, an object does not have a name. In fact, having a name is fundamentally not how Python's type system functions, although modules, types and functions are created with __name__ attributes.

In [12]: compile("First = Myclass('firstvar','secondvar','thirdvar')", "sample", "single")
Out[12]: <code object <module> at 0xf5fde458, file "sample", line 1>

In [14]: dis.dis(Out[12])
  1           0 LOAD_NAME                0 (Myclass)
              3 LOAD_CONST               0 ('firstvar')
              6 LOAD_CONST               1 ('secondvar')
              9 LOAD_CONST               2 ('thirdvar')
             12 CALL_FUNCTION            3
             15 STORE_NAME               1 (First)
             18 LOAD_CONST               3 (None)
             21 RETURN_VALUE

Note that the name First has not appeared at all until after Myclass is called using CALL_FUNCTION. The object returned by Myclass therefore has no clue about the existence of First (indeed, it doesn't exist until after the assignment STORE_NAME). The only way it could be found would be some insane black magic by tracing back the stack to find at what point the caller called the constructor and then interpret the future execution to find the name; and it is not guaranteed to even exist, let alone be as easy to understand as this sample.

What your object has, however, is an identity. Identities are not universally unique, but while the object exists, no other object has the same identity within the same process. You could find that identity using id(self), and the default stringification also includes it: str(f) produces things like <__main__.Foo instance at 0xf603f46c> (names of the module and class, while the instance id is printed in hexadecimal).

Once the name does exist, it is not a property of your object, but an entry in the namespace of the executed code (might be a module or a function call). It can equally be assigned into any other similar entries, such as attributes of other objects, and none of them are particularly authoritative; each points to the same unnamed object.

If you do want to name your objects, the easiest way is to simply pass a name to the creation, as with all your varN attributes.

Python: Referring to any created object with __init__

Python: Referring to any created object with init