Getting an instance name inside class __init__()

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While building a new class object in python, I want to be able to create a default value based on the instance name of the class without passing in an extra argument. How can I accomplish this? Here's the basic pseudo-code I'm trying for:

class SomeObject():
    defined_name = u""

    def __init__(self, def_name=None):
        if def_name == None:
            def_name = u"%s" % (<INSTANCE NAME>)
        self.defined_name = def_name

ThisObject = SomeObject()
print ThisObject.defined_name   # Should print "ThisObject"
instance object class python variables
10 Answers

The best way is really to pass the name to the constructor as in the chosen answer. However, if you REALLY want to avoid asking the user to pass the name to the constructor, you can do the following hack:

If you are creating the instance with 'ThisObject = SomeObject()' from the command line, you can get the object name from the command string in command history:

import readline
import re

class SomeObject():
    def __init__(self):
        cmd = readline.get_history_item(readline.get_current_history_length())                                                          
        self.name = re.split('=| ',cmd)[0]

If you are creating the instance using 'exec' command, you can handle this with:

if cmd[0:4] == 'exec': self.name = re.split('\'|=| ',cmd)[1]     # if command performed using 'exec'
else: self.name = re.split('=| ',cmd)[0]
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